The Nuts and Bolts of Vaccines Against SARS-CoV-2

The groundbreaking cooperation between medical experts across the globe has made a return to normal possible thanks to the COVID-19 vaccines. The speed of development was due to the sharing of research on a scale never attempted before, and every study was carefully reviewed and approved by a safety board and the FDA. The process was transparent and rigorous throughout, with oversight continuing for two years after each vaccine is first administered to ensure that the long-term effects are safe.

Many people are skeptical or concerned about side effects, and we hear you. Good, evidence-based information about the vaccine has been hard to come by, so we've put together the following FAQs to cut through the uncertainty.

Returning to this page? New topics from the last update on July 26, 2021 are marked with a plus sign.

In general, how do we know vaccines work?

Short Answer: In a vaccine study, half the people are given the vaccine, and half are not. If the people given the vaccine get sick less than half as much as those who got the vaccine, we consider that the vaccine worked.

Expanded Answer: The obvious way to prove a vaccine works is to vaccinate people, expose them to the virus, and see if they get sick. But that's unethical. Instead, we recruit people for whom the vaccine is appropriate and give half of them the real vaccine. The other half receives a placebo injection that contains no active vaccine (some trials use two-thirds vaccine and one-third placebo). Then everybody is monitored to see if they get sick. Statisticians can tell us how many people need to get sick in the placebo group before finding out if the vaccine worked.

The FDA's standard of efficacy is 50% – people who received the vaccine need to get sick no more than half as often as those who did not receive the vaccine for it to be considered effective. Among the 43,448 participants in the Pfizer trial, the first COVID-19 vaccine trial to be completed, the half who received the vaccine experienced only nine infections. Those who did not receive the vaccine suffered 169 infections, showing a vaccine effectiveness rate of 95%. The FDA would have considered the vaccine effective if as many as 84 vaccinated participants became infected, but only nine of them actually did.

What does the COVID-19 vaccine do?

Short Answer: The vaccine helps us make our own antibodies against what's called the 'spike' protein of the virus, which makes it much harder for us to get infected.

Expanded Answer: What makes the SARS-CoV-2 virus (the name of the virus that causes the disease we know as COVID-19) unique is its spike protein, which are the red things you see in the depictions of the coronavirus. They attach to a protein on human cells called the ACE2 receptor, allowing the virus to gain entry to our cells, where it takes over our cell machinery to make more copies of itself. So the strategy is to get people to make antibodies against this spike protein without getting infected. Once we have our own antibodies against the spike protein, if we then get exposed to the virus, our antibodies latch onto the spike protein. Once the spike protein is covered with antibodies, it can't attach to the ACE2 receptor and can't infect our cells. Unable to make more copies of themselves, the inactivated virus particles can be quickly eliminated by our immune system.
What is the problem with the new variants and the vaccine?

Short Answer: We use the term variants to describe new strains of the virus with altered spike proteins, which might make the vaccine less effective.

Expanded Answer: One way to think of the immune response to a virus would be to think of it as a lock, which holds back the floodgates of an effective attack against the virus. The vaccine tells our immune system how to make the lock by showing it the spike protein (the key). Then, when the same virus comes back – that is, the key unlocks the floodgates – our immune systems react strongly and swiftly to hopefully prevent infection, or at least keep it less severe. Over time, as the key gets banged up (variants emerge), the key will still work, but maybe not as well – it doesn't turn smoothly, or it takes more force to turn it. Eventually, the shape of the key becomes so different that it no longer opens the lock. That's where the concern is. As the SARS-CoV-2 spike protein mutates into new variants, the antibodies we've made in response to the vaccine might no longer recognize the new spike protein, and a preventive immune response won't be triggered.
What is an mRNA vaccine?

Short Answer: This is a newer vaccine technology that uses the genetic material for a virus's most crucial protein. A considerable advantage of this technology includes producing the vaccine directly and rapidly in the lab, rather than first cultivating large amounts of the actual virus as starting material. It is harder to distribute the vaccine because the genetic material has to be frozen, but the advantage is that there is no need to add any antibiotics or preservatives. Thus, mRNA vaccines are safer for people who are allergic to these things in other medications or vaccines. The mRNA breaks down in a few days, so there are no traces of the vaccine other than the antibodies we used it to produce.

Expanded Answer: Messenger RNA, or mRNA, is the genetic material that tells our cells how to make a specific protein. If we were to simply inject the spike protein into people, enzymes in our bloodstream would break down the proteins, preventing us from making antibodies against it. Instead, we first make the genetic material that holds the spike protein code. We would also break down plain mRNA that gets injected into us, so we have to wrap it up in material that helps it get into our cells. Once inside, the mRNA tells our cells how to make the spike protein. The muscle cells making this protein show it to our immune system, which recognizes that it is a foreign protein and starts to produce antibodies against it. Messenger RNA doesn't last a long time, so after our cells have used it for a few days to make the spike protein, the mRNA just breaks down inside the cells, and our cells recycle its parts as part of our day-to-day life.
'Genetic material' sounds scary. Does it get into our DNA?

Short Answer: Absolutely not. That is not what mRNA does, and the claims we hear about mRNA vaccines changing our DNA are nothing more than an uninformed scare tactic.

Expanded Answer: Our cells make proteins coded by our DNA in the cells' nucleus. When our cells want to make proteins, parts of the DNA code are copied into mRNA. The mRNA moves out of the nucleus, where little organelles called ribosomes read the mRNA code using transfer RNA to make the correct proteins. After a few days, the mRNA is broken down and recycled by the cells. This process is a one-way street, because our cells don't have the machinery to go backwards - mRNA does NOT go back into the nucleus to get back-translated into DNA. Ever.

Recent studies have examined people in whom the PCR test remains positive long after the infection, and it has been shown that this is due to small pieces of viral genetic material getting incorporated into the patient's DNA. The evidence indicates this is due to current infection with other viruses that do have the machinery to do this, and with the widespread replication of virus RNA throughout the body during an infection, some of that RNA gets accidentally reverse translated into the human genome. Of course, reverse transcription can only occur with RNA, which is what comprises the genome of the intact virus – messenger RNA, the genetic material in the vaccines, cannot undergo what would have to be a two-step process, reverse transcribing it first into RNA and then again into the patient's DNA. There is no cellular mechanism for translating mRNA back into RNA. So the risk of viral RNA showing up in a person's DNA is only after an actual infection, not a vaccination, adding to the reasons for getting vaccinated.

This new technology was developed awfully fast – is it really safe?

Short Answer: It is true that there are no other mRNA vaccines previously manufactured, but the technology is not new. mRNA technology has been used for fifty years, and efforts to use mRNA specifically for vaccines have been ongoing for the past twenty years.

Expanded Answer: The first time a cell made a foreign protein from injected mRNA was in 1971. The first time we induced living mouse muscle tissue to make foreign proteins from mRNA was in 1993. The first mRNA vaccine was developed against rabies and entered clinical trials in 2013, but this was a proof-of-concept trial and was not used to make a commercial vaccine. We started to develop mRNA vaccines against SARS and MERS, but those viruses were so lethal that they burned themselves out, and there was no need to bring the vaccines to market. SARS-CoV-2 very rapidly showed that it would be a significant threat to the planet, so we picked up where we left off with mRNA vaccine development and hit the ground running. The first clinical trial of an mRNA vaccine started just 66 days after the genome of SARS-CoV-2 was sequenced - you can't move that fast if you're not well prepared for it.
The trials were completed in only nine months or so – didn't they cut a lot of corners to do it so fast?

Short Answer: The time it takes to develop a vaccine depends on the population who needs it and how common the disease is. These vaccines are intended for all adults (initially) for a disease striking 60,000 to 100,000 people per day (in summer and fall 2020). That makes it easy to generate a lot of important information very quickly.

Expanded Answer: Many of the vaccines we use were developed for children, and that process can take a decade or more. That's why it's easy to think that the COVID-19 vaccine trials were rushed. But as we discussed how we find out if a vaccine is effective, that is a function of the disease. There are several reasons why childhood vaccines take so long. First off is the slow recruitment rate - we can't enroll babies into these trials any faster than they're born. Secondly, many parents will not enroll their newborn in a clinical trial of a vaccine. So the trials are slow to enroll, and the diseases we're trying to prevent aren't very common in this country. So it takes a very long time to get enough infections in the placebo group to see if the vaccine did anything at all. But for COVID-19, practically anybody over age 17 who wasn't infected with SARS-CoV-2 at the time, didn't have any significant, unstable medical problems, and who wasn't pregnant or nursing was eligible. And instead of studying a vaccine for a relatively uncommon disease, we saw over 50,000 new cases in the US every day during these trials. In fact, that was a strategy for recruitment - the people running the trials specifically looked for parts of the country where the disease was most active. You'll get the required number of infections in the placebo group much faster if you conduct the trial in an area getting 1,000 new cases a day rather than 20.
I've heard reports about reactions to the vaccine. Is that worrisome?

Short Answer: Adverse reactions to the vaccine are rare because of the way the vaccine is prepared. The only people advised to be cautious about getting the vaccine are those who have had severe reactions to injectable medications in the past. If you have had a severe reaction to an injectable medication that required treatment, talk to your doctor or allergist/immunologist about whether to get the vaccine.

Expanded Answer: The mRNA in the vaccine is essentially the same as the mRNA for the spike protein in the virus. The main difference is the wrapper that is used to get the mRNA into our muscle cells. It does contain polyethylene glycol, which is known to cause allergy-like reactions in some people. Allergies to other common allergens like pollens, molds, dust mites, foods, or latex do not put people at increased risk of vaccine reactions. The vaccine is distributed in a deep freeze, so there is no need for any antibiotics or preservatives. Since we don't have to grow the viruses in the lab to make mRNA vaccines, there is also no egg or gelatin in the vaccine. So the vaccine should be used with caution in people who have reacted to other vaccines or medications containing polyethylene glycol or polysorbate 80, or if they have conditions such as mast cell activation syndrome that put them at greater risk of severe reactions to a variety of things. But the vaccine is safe for almost everybody.
I've seen reports on social media that the vaccines have caused over a thousand deaths. Where's the outrage?

Short Answer: This refers to VAERS, the Vaccine Adverse Event Reporting System. All of these reports have been or are being investigated, and to date none of these deaths have been shown to have actually been caused by a COVID-19 mRNA vaccine. There have, however, been 4 reports of death due to cerebral venous sinus thrombosis after the Janssen vaccine.

Expanded Answer: The VAERS is a voluntary reporting tool – anyone can submit an adverse event report to VAERS. This means that non-medical people who do not have the knowledge base and experience to truly know whether a death was related to a vaccine can make a report anyway, and once it's been submitted, it's counted. It also means that anyone out to discredit the vaccines can go ahead and report a death for any reason as having been related to the vaccine. But even at that, with over 305 million doses administered thus far in the US, only 0.001% have been reported as having died some time afterward, a bit lower than the risk of being struck by lightning.

The Advisory Committee on Immunization Practices continued to recommend that the benefits of vaccination outweigh the risks as of August 13, 2021. Additional information about adverse events is also available from the CDC.

Can the vaccine make me sick? What about all the side effects I've heard about?

Short Answer: No. The vaccine is not made from live virus particles, so there is no possible way to get infected by the vaccine. Many people have some symptoms of a robust immune response to the vaccine, but this is expected, is typically mild, and lasts only one or two days.

Expanded Answer: You cannot get infected from the vaccine. There is no virus in the vaccine, only the mRNA for the spike protein, and not anything else required for viruses to cause an infection. However, what is critically important is that most of the symptoms that people associate with viral infections are symptoms caused by the immune system in its response to the vaccine, not the infection itself. Not everybody experiences these symptoms, but it is expected that many people will notice a mild fever, muscle aches, fatigue, chills, or joint pain that can last for 1-3 days after vaccination. This is only a sign that your immune system is doing what it is supposed to do. The reason this is important enough to use bold type is that there is a concern that people who experience these symptoms after the first dose will think that the vaccine made them sick, and they won't go back for the second dose. This would be a critical mistake. The studies have shown that while there is an antibody response after the first dose, that first dose "primes the pump" for the second dose, after which antibody levels soar to levels so high that the vaccine is 95% effective at preventing infection. You can't expect the vaccine to work that well after just one dose, so please be sure to go back for the second.
I've heard that people who get vaccinated are shedding virus and can be a threat to others around them. Is this true?

Short Answer: Absolutely not. This is nothing more than an uninformed scare tactic.

Expanded Answer: This concern arises from live attenuated vaccines, such as the one we have for polio. However, as you've seen throughout this page, the mRNA (DNA in the case of the Johnson vaccine) is synthesized in the lab and is not derived from virus culture, so there is no possibility of giving someone the entire viral genome with which intact virus particles could be made. This claim is simply a deliberate scare tactic.
Can I get the COVID vaccine even though I have a sinus infection?

Short Answer: If you have the opportunity to get vaccinated or have significant potential risk such as exposure to the public with your job, go ahead and get the vaccine. But if you have low exposure and it is reasonable for you to wait, then it'll be best to wait until you're over the infection.

Expanded Answer: Our immune system works best when it can focus. Just like we do a better job when we're focused on one objective rather than multi-tasking, our immune system works best when it is focused on one thing. If your immune energy is occupied with fighting off a sinus infection, it can't do as good a job processing the vaccine. It will, so you can go ahead, but you might get a better immune response if you don't have any other distractions for your immune system to divide its attention. But also be aware that the COVID vaccines strongly activate the immune system, and many people do experience symptoms of a robust immune response for 24-48 hours after the COVID vaccine. If you already have an active immune response to the sinus infection brewing, the additional response to the vaccine might make you pretty miserable for a couple of days while theoretically also helping you fight off the sinus infection.
I'm young and healthy, and COVID-19 doesn't seem to be a big deal in my age group. Shouldn't I just get it over with, and develop better immunity by getting the infection?

Short Answer: No. The mRNA in the vaccine helps us make antibodies against the spike protein, just like we do with COVID-19 infection. But with infection, the virus forces us to make ALL of its proteins and make more copies of the virus itself. That's what triggers the severe illness many people get with COVID-19, and the risk of long-term complications. None of that happens from the vaccine.

Expanded Answer: A major feature of SARS-CoV-2 is that it is so unlike any other viruses before it that essentially none of us are immune. That's why it's called a 'novel' coronavirus. If we are significantly exposed, we will get infected. Almost everybody will likely have to develop immunity either the hard way (getting infected) or the easy way (getting vaccinated). So it is useful to compare the risk of the vaccine with the risk of getting infected. That makes it easy – with vaccines for the spike protein, we start making the spike protein to show to our immune systems just like we would if we were to get infected – but without all the other proteins and without the genetic material of the virus as a whole. So it is far safer to get vaccinated instead of wait to get infected. And we see that in the numbers: more than one in 46 people with COVID-19 worldwide have died from the infection, but only about 1 in 100,000 people has significant reactions from the vaccine. These are all treatable, so these folks do carry on with their lives. As of this writing, there have been 176 million COVID-19 infections resulting in over 3.8 million deaths, killing people of all ages as young as two months. Of the 480 million people fully vaccinated worldwide with over 2.25 BILLION doses administered so far at the time of this writing (June 15th), there have been zero deaths attributable to the vaccines. Protecting yourself with the vaccine is clearly the best way to go, so when the vaccine becomes available to you, please roll up your sleeve!
I am pregnant or planning on getting pregnant. Should I get the COVID vaccine?

Short Answer: This question really boils down to the mother's risk of infection. If she is able to avoid public exposure and have minimal risk of getting COVID-19 for the entire pregnancy, it could be reasonable to wait. But if mom is not able to minimize her risk of getting infected, it would be best to get vaccinated. Both the American College of Obstetrics and Gynecology (ACOG) and the Society for Maternal and Fetal Medicine (SMFM) recommend that pregnant women be vaccinated.

Expanded Answer: Because of the way the new vaccines work, there is no reason to expect that there would be any complications from the vaccine that wouldn't occur with an infection. Of course, the symptoms of an infection would be much worse, and COVID-19 infection carries significant risk of long-term complications for mom. There is limited information about the effect of COVID-19 infection on a fetus and newborn, and of course, this disease has not been around long enough for us to have any idea about possible long-term complications for the baby if mom gets COVID-19 while she is pregnant and the baby then gets infected from mom. Because of the long-term complications we are seeing in adults, it is likely best to do what we can to avoid the baby getting infected. We have long known that antibodies from the mom do cross the placenta; that is a major source of immunity in newborns that helps prevent infections in the first few months of life. Limited studies in pregnant women done thus far have shown that the antibodies stimulated by the COVID vaccines also cross the placenta and can be found in the baby, helping prevent the baby from getting infected if exposed after delivery.
Will getting vaccinated hurt my chances of having a baby in the future?

Short Answer: Both the American College of Obstetrics and Gynecology (ACOG) and the Society for Maternal and Fetal Medicine (SMFM) find there is no suggestion of any effect of the vaccine on fertility.

Expanded Answer: The vaccines are too new for us to have prospective, observational data on fertility. However, since the vaccines essentially do nothing other than a subset of what happens during coronavirus infection (ie, using viral mRNA to make the spike protein to induce an antibody response in the same way that happens during an infection, but without the other viral proteins and the rest of the viral genome), it is appropriate, reasonable, and reassuring to note that after at least 176 million infections worldwide, there has been no observable effect on fertility among those who survived the infection. Further, we can think of death as the ultimate adverse effect on fertility. Although it is true that the risk of death increases with age, as of this writing, there have been 3289 deaths from COVID-19 among women of child-bearing age in the United States alone.
I keep hearing about variants – what does that mean?

Short Answer: Variants are new strains of a virus that come about when mistakes are made while copying the genetic information. The importance of the variants to the COVID-19 pandemic is that the ability to infect human cells may change if the spike protein is altered.

Expanded Answer: During an infection, when the coronavirus takes over our own cells' machinery and forces our cells to make new copies of the virus, errors are made when the genome is copied or transcribed. Many of these are minor and don't seem to make any difference. Some are catastrophic – a single change might code for a protein that takes a wrong turn at a given point, for example, and the protein can't do its job anymore. These mutations just die out because the virus can no longer cause itself to be replicated. The concern for the pandemic is twofold: 1) With regard to the lock-and-key analogy above, mutations and variations in the spike protein could change the shape of the protein so much that the antibodies we're making in response to the vaccine can no longer bind, and we lose that protection. We already see a decreased effectiveness of our current vaccines to some of the new variants. 2) These same variants (the banged-up key in our analogy) might actually bind more tightly and more strongly to the ACE2 receptor. This can make the virus more contagious since it wouldn't take much exposure to get past our bodies' defenses, and it can also potentially make the illness more severe.
What do I need to know about the Delta variant?

Short Answer: It is more contagious than the original strain, and symptoms are more likely to be headache and fever than the loss of smell and taste with the original strain. Importantly, it is twice as likely to cause hospitalization in unvaccinated people, and in just three months is the predominant strain in the UK and is causing well over 50% of all new infections in the US.

Expanded Answer: An important feature of the Delta variant to keep in mind is that it first emerged as COVID-19 was spreading rapidly throughout India in April of 2021. In just a few months, it spread across the globe and became the prominent strain in the UK and has been identified in all 50 states by July. The Delta variant is 60% more contagious than the Alpha variant, which itself is 50% more contagious than the original Wuhan strain. It was announced in June that it is expected that the Delta variant will soon overtake the Alpha variant in the United States. Fortunately, although the vaccines do not seem to be as effective against the Delta variant and its related Delta-plus variant, they still offer good protection.
So isn't this a losing battle? If we already have variants that can get past the immunity we get from the vaccines, why bother?

Short Answer: Viruses mutate by moving through people. The more we do to limit the spread, including vaccination, the more we decrease the ability of the virus to mutate, keeping our vaccines more effective.

Expanded Answer: As above, viruses mutate in the process of replication. So when we are not taking precautions, sharing the virus freely, and see infections sweep through a community or a country, the high rate of virus replication increases the chances that mutations will occur. So the more we do to limit the spread of the virus – vaccination, mask-wearing, hand-washing, social distancing – the slower the virus will mutate, and the longer our current vaccines will be effective. So it is true that our vaccines are less effective against some of the new variants, but vaccination remains an essential part of limiting the spread and giving the virus less chance to mutate.
I've been waiting a year for the vaccine to finally come out so I can get back to my life. But now that I'm vaccinated, some people are saying we should keep on mask-wearing and social distancing anyway, even though these restrictions are being relaxed! Why?

Short Answer: No vaccine can be 100% effective. Because the vaccine makes illness less severe, it is possible for vaccinated people to get an asymptomatic infection and spread the disease to others. Limited data we have suggests this risk is very low, but not zero.

Expanded Answer: It is the antibodies secreted into respiratory secretions, not in the bloodstream, that are protective. If you get exposed to respiratory droplets that contain virus, it is the antibodies in the fluid covering the eyes, nose, mouth and lungs that have to latch onto the spike proteins to prevent all those virus particles from infecting us. So if you have a huge exposure (for example, an infected person suddenly sneezes on you), you might not have enough antibodies lining your respiratory tract to prevent infection. But if you get infected, the antibodies in the bloodstream will limit the infection, so you might not even know it. We don't know how much this happens – to find out, we have to go out and randomly test many people who have been vaccinated, and we just don't have the resources to do that. But in certain circumstances (for example, the mandatory testing required prior to elective surgery), we have seen very low numbers of vaccinated people testing positive. So continuing to reduce your exposure after vaccination helps to prevent getting infected, prevents you from unknowingly infecting others, and helps to encourage everybody to keep taking care to prevent the spread, whether vaccinated or not.
I look around, and almost nobody is wearing masks - the pandemic must be over. Why vaccinate now?

Short Answer: No, the pandemic is far from over, with only about half of the world's population not vaccinated yet. Vaccination protects against infection, protects against severe disease, and protects our children. No vaccine is yet approved for under age 12, so the more people age 12 and over get vaccinated, the less likely children under 12 will get infected.

Expanded Answer: Infections have slowed down, but enough people remain at risk of infection that it is important to continue efforts to limit the spread. Even more importantly, hospital systems across the globe are reporting that more than 90-95% of people getting hospitalized or dying from COVID-19 are unvaccinated - although no vaccine is 100% protective against getting infected, people who get infected after vaccination almost never get severely ill. The current vaccines are highly effective at preventing severe disease.
Are we going to need booster vaccinations, like we do with influenza?

Short Answer: Likely, but we don't have enough information yet to know how often we might need boosters and whether we will need to change the vaccines from time to time.

Expanded Answer: We continue to gather data about how long the immunity lasts and how well the antibodies produced by the vaccines protect us from the new variants. The original Moderna and Pfizer studies are two-year studies in which the participants – who were vaccinated in summer 2020 – come back periodically to have their blood drawn to check their antibody levels. So by the end of 2021, we'll have good data on how long protective antibody levels last, and that will give us an idea of whether and how often we'll need boosters. Studies are also ongoing as to how well the antibodies we make in response to the vaccines protect us from the variants. The beta variant (formerly B.1.351) seems to not be well covered by the current vaccines, and Moderna already has a study underway of a modified vaccine specifically for this variant. We'll have to monitor how well we stop the spread and limit the emergence of new variants to see whether we'll need to re-vaccinate with modified vaccines from time to time.
I take vitamin C, vitamin D and/or other supplements to boost my immune system, so I don't have to worry about getting COVID-19, right?

Short Answer: There is no such thing as "boosting" the immune system. And although these supplements might be helping the immune system to work at peak performance, they do nothing about preventing infection in the first place, as the antibodies produced by the vaccine do.

Expanded Answer: The immune system knows what it's doing, and it does it very well. However, the immune system, along with other systems and enzymes in the body, needs cofactors such as vitamins and minerals in the diet to keep everything working normally. So all you need to do is give the immune system the tools it needs to do its job – giving it more than it requires won't help it work any better. Your Honda Civic will run great if you keep the air filter and oil changed as often as recommended and filled with gas – but more gas or a better grade of oil still won't get you winning the Indy 500 with it.

But if a well-functioning immune system were enough, we wouldn't see appreciable case fatality rates. That's because once an infection starts, our immune system is often not powerful enough to stop it. So we have to prevent the infection in the first place. That starts with distancing and masking to reduce the chances of getting exposed to the virus and getting vaccinated to generate enough antibodies so that when we do get exposed, these antibodies latch on to the virus and prevent it from infecting us, which is something that only antibodies can do – vitamins and immune supplements cannot do this.

People die of respiratory illnesses every year - did COVID-19 really make that big a difference?

Short Answer: Yes. Between March 1, 2020 and January 2, 2021, there were 2.8 million deaths in the US, about 23% more than expected. Most of these were due to COVID-19.

Expanded Answer: The excess deaths in 2020 (23%) is substantially more than in recent years (<2.5%). Of those, 72% were attributed to COVID-19, and these deaths reflected racial disparities in COVID-19 (highest among non-Hispanic Black). Many of the excess deaths not due to COVID-19 were due to heart disease, dementia, and diabetes, and these excess deaths were associated with surges in COVID-19 activity. It is widely believed (though difficult to prove) that many of these deaths were due to delayed care during surges - people reluctant to go to the hospital for fear of being exposed to COVID-19 patients. for more information: Woolf SH, Chapman DA, Sabo RT, Zimmerman EB. Excess Deaths From COVID-19 and Other Causes in the US, March 1, 2020, to January 2, 2021. JAMA. 2021;325(17):1786-1789. doi:10.1001/jama.2021.5199
I had COVID last year, so I have my own natural immunity and don't have to get vaccinated, right?

Short Answer: Not really. Now more than a year into the pandemic, we're starting to see studies done in people with prior infection, and the protection from that natural immunity is not as strong as the protection we get from the vaccines.

Expanded Answer: Recent studies have looked at the Delta variant because of how rapidly it is expanding across the planet. The mRNA vaccines (Moderna and Pfizer) are highly effective against the Delta variant at 88% protection (compared to 90-95% against the original strain), although only about 33% effective after just one dose. The Johnson vaccine is about 60% protective against the Delta variant, and about 66% against the original strain. Importantly, some preliminary laboratory studies showed that antibodies from fully vaccinated people are much more effective at blocking the Delta variant than antibodies from partially vaccinated people. In fact, the additional protection after the second vaccine dose is much greater with the Delta variant than the Alpha variant, underscoring the need to get both doses. Lastly, studies with antibodies from people who recovered from COVID-19 a year earlier showed they did not do a good job at blocking the Delta variant, but after these people were vaccinated, their immunity against the Delta variant was just as strong as other vaccinated people.