By Madeline Keleher
Dec 21, 2021
Some claim that boosters for COVID-19 are unnecessary for certain people or even unethical—but is that right? Let’s look at the data.
Why boost ever?
Oftentimes, live vaccines give enough protection after just one dose, but non-live vaccines need multiple doses spaced at least 4 weeks apart (although a longer time interval is often considered better). Boosters are generally given at least 6 months after the primary series of shots. It’s not just COVID-19—at least three vaccine doses are required for sufficient protection against lots of diseases, including Hepatitis B, diphtheria, tetanus, pertussis, and polio. It appears that the new mRNA vaccines are no exception. A study published in Nature found that compared to one dose, a second dose induced a vastly stronger and better immune system response to the coronavirus. And three doses are better than two.
What are the arguments against boosting?
There are a variety of reasons people do not want to get a booster shot. One is believing that boosters are unnecessary for many people (a common belief in the scientific community this past fall). Another reason is fearing rare but serious side effects. Some people worry about anaphylaxis (although anaphylaxis is treatable and the chance of developing it after mRNA vaccination is a minuscule 0.0005%). Some younger men fear myocarditis (although their chance of developing myocarditis is 9 times higher if they are infected with COVID-19 than after vaccination: 0.09% vs. 0.01%). Some people still worry that the mRNA vaccines are not safe (even though the vaccines were shown to be safe in large clinical trials, and their safety record still holds now that millions of people have been inoculated).
Then there are people like me, confident in the safety of the vaccines but concerned about vaccine inequality. Over 40% of the world has not received even one COVID-19 shot—and the numbers are worst in low-income countries, where 92.4% of people have not been vaccinated. As the emergencies chief of the World Health Organization put it, it’s like we are handing out life jackets to the people who are already wearing life jackets instead of to the people who are drowning. And when he said that back in August, I agreed. I supported boosters for the highest risk individuals, but as a healthy young woman I did not plan to get a booster myself. Then came Omicron. Omicron changed the numbers, and the numbers changed my mind.
What evidence supports boosting?
1) Survivors of COVID-19 are being re-infected with Omicron.
In the few weeks that we have known about Omicron, this new variant has re-infected many people who had already recovered from COVID-19. A new study from South Africa indicated that people are at a much higher risk of reinfection from Omicron than they were from Beta or Delta. Scientists in the United Kingdom estimated that the chance of reinfection is 5.4 times higher with Omicron than it was with Delta. While prior coronavirus infection used to give 85% protection from being infected again in the next 6 months, there appears to be only 19% protection from Omicron.
Antibodies are like keys that come in all different shapes and sizes, and viruses are like locks. Your body will try out different antibody keys on a virus, searching for a key that fits the lock. When the key fits, your immune system can attack and destroy the virus. If you get re-infected by the same virus, oftentimes your immune system remembers the right key, makes more of it, and quickly wins the war. But Omicron is a variant that has drastically changed the shape of its lock. Your keys may no longer fit.
2) Two vaccine doses do not protect well against Omicron infection.
Two-doses of the mRNA vaccines protected strongly against Alpha and Delta; that is not the case with Omicron. 3D modeling of the fit of 132 known antibodies onto Omicron’s heavily mutated spike protein indicated that Omicron is two times more likely than Delta to escape current vaccines and won’t be as responsive to many current monoclonal antibody treatments. Tests done in labs on the blood of vaccinated people revealed that their antibodies were far less effective on Omicron. Antibodies from two doses of Pfizer were 25 times less potent against Omicron than the original coronavirus strain. Antibodies from two doses of Moderna were 41-84 times less potent against Omicron than the main May 2020 form of the virus. Even worse, preliminary research shows that the vaccines from AstraZeneca, Johnson & Johnson, China’s Sinopharm, and Russia’s Sputnik V do very little at all to stop Omicron infection.
3) A third mRNA dose is far more protective than two doses.
A third dose of an mRNA vaccine drastically increases antibody levels: Pfizer’s by a factor of 25 on average and Moderna’s by a factor of 37.
A study of over 843,000 people aged 50 or older in Israel found that those who had received a booster died of COVID-19 at a 90% lower rate than those who had received just two Pfizer doses. An even larger study of over 1.1 million people aged 60 or older found that compared to those with just two doses of Pfizer, people who were boosted were 11.3 times less likely to get infected with the coronavirus and 19.5 times less likely to have severe COVID-19.
Both of those studies involved people over the age of 50, so you may be wondering: does this apply to younger people? Yes! A study of over 4.6 million people aged 16 and up found that the protective effect of a booster dose was massive at all ages: boosted 16–29-year-olds were 17.2 times less likely to be infected than those with only two doses, people in their thirties 9 times less likely, people in their forties 9.7 times less likely, and those in their fifties and above were 12 times less likely to be infected by the coronavirus if they'd had three doses instead of just two.
4) Omicron is the most contagious variant yet.
It appears that Omicron is 10 times as contagious as the original coronavirus (twice as contagious as Delta), according to early modeling (we’ve known about Omicron for just a month, so at this point, it’s all early).
5) A more contagious variant means more deaths.
Is Omicron milder? Maybe, maybe not. It's too soon to tell. But even a milder variant can wreak havoc when it's this contagious. Currently, 61.4% of the US population has completed the initial phase of vaccination and a mere 29.1% is boosted. This means that less than one-third of the US population has good protection against Omicron, leaving most people susceptible to being infected by and spreading a highly contagious virus. No matter which variant we've been on, the number of COVID-19 cases has been strongly correlated with the number of deaths. Deaths rise predictably 1–2 weeks after cases rise: check out the relationship visually here or here. As Omicron sends the world into the throes of a new pandemic wave, deaths will surge.
In my early twenties I didn’t get flu shots, worried I’d be taking one from someone who needed it more. Then, while riding a city bus, I saw a poster of two seated bus passengers. Germs floated around them and the text above them said something to the degree of: “even if you feel healthy, you may have just killed the person sitting next to you: get your flu shot.” Horrified, I have gotten a flu shot annually ever since. Similarly, getting a COVID-19 booster isn’t really about you: it’s about everyone else.
6) More variants are coming.
In time pi, rho, sigma, tau, and so on will emerge as variants of concern. How do we know? All viruses mutate. The coronavirus typically gains 1 or 2 mutations a month. Flu viruses mutate so quickly and there are now so many strains that there may never be a universal flu vaccine (and that’s why the flu shot is different every year). We may be headed that way with COVID-19, though it’s possible that after three doses you’re really done. It is too soon to tell.
Omicron has over 30 mutations in its spike protein alone. Its spike is so different from the original coronavirus that the way Omicron is detected by some PCR tests is by not detecting the spike (while still detecting two other parts of the virus). Some types of PCR tests that rely only on detecting the spike protein don’t work at all on this new variant. Omicron has changed the locks on us.
Omicron likely originated in one immunocompromised person who was infected with the virus for months. Protracted viral infection in a person with a weakened immune system is a recipe for disaster. The average generation time in humans is commonly estimated as 29 years; for the coronavirus it is 5.7 days. An immunocompromised person infected with COVID-19 for 6 months would incubate about 32 generations of the virus, giving it a safe place and plenty of time to try out lots of new mutations and keep the ones that help it evade the immune system. The virus emerges at the end of that process heavily mutated. Researchers have watched this unfold before their very eyes during the pandemic.
For instance, a woman in her thirties with advanced HIV battled COVID-19 for more than 7 months. Scientists sequenced the virus’s genome from her throughout the whole process, documenting in real time the virus acquiring many mutations to escape her antibodies. Likewise, a cancer survivor in her forties was infected with COVID-19 in 2020, and as she fought it for months the virus acquired mutations that would later be found in the Alpha, Gamma, and Delta variants when they took hold.
It is unknown exactly how many people worldwide are immunocompromised, but about 3% of American adults are, so in the US alone there are millions of people with compromised immune systems. Any one of them can be taken advantage of by the coronavirus. The whole world is under-vaccinated, Omicron is spreading like wildfire, and new variants are already forming unnoticed. What the world needs for Christmas is boosters.
Who can get a booster?
Anyone aged 16 or older can get a COVID-19 booster shot (as of the time of publication).
When can I get a booster?
You can get a booster 2 months after receiving a Johnson & Johnson vaccine or 6 months after receiving an mRNA vaccine.
How can I schedule a booster?
There are many ways to schedule a booster, including through Walgreens, Walmart, Safeway, and CVS. A lot of communities have centers offering walk-in appointments, too.
How much will my booster cost me?
Absolutely nothing! COVID-19 boosters are free to everyone living in the United States, regardless of immigration status or if they have health insurance.
Happy holidays, everyone (but first, please get boosted)!
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