--- title: Why You'll Need to Get COVID-19 Boosters Again and Again description: Two leading epidemiologists explain why you'll be getting many COVID-19 boosters in the years ahead because that's how the vaccines work canonical: https://time.com/6198402/covid-19-boosters/ author: Akiko Iwasaki article:opinion: true article:content_tier: free article:published_time: 2022-07-19T11:00:10.000Z article:modified_time: 2026-10-14T09:37:40.999Z article:section: Ideas og:title: Why You'll Need to Get COVID-19 Boosters Again and Again og:description: Two leading epidemiologists explain why you'll be getting many COVID-19 boosters in the years ahead because that's how the vaccines work og:url: https://time.com/6198402/covid-19-boosters/ og:site_name: TIME og:image: https://static.time.com/v3/assets/bltea6093859af6183b/blt8c4ab2c6b4910b6e/698a33d222fb859f0fe2dada/GettyImages-1389964175.jpg?branch=production&width=1024&quality=75&auto=webp&crop=16:9 og:image:width: 1024 og:image:height: 576 og:image:alt: U.S. FDA Authorizes Second COVID-19 Booster Shot For Those Over 50 og:type: article twitter:card: summary_large_image twitter:title: Why You'll Need to Get COVID-19 Boosters Again and Again twitter:description: Two leading epidemiologists explain why you'll be getting many COVID-19 boosters in the years ahead because that's how the vaccines work twitter:image: https://static.time.com/v3/assets/bltea6093859af6183b/blt8c4ab2c6b4910b6e/698a33d222fb859f0fe2dada/GettyImages-1389964175.jpg?branch=production&width=1024&quality=75&auto=webp&crop=16:9 ---  # Why You'll Need to Get COVID-19 Boosters Again and Again > Sponsored content. Supplied in partnership with TIME. TIME is the sponsor and source of this material. > Last updated: September 2026. ## TIME Newsletters: Reference Facts and FAQ ### Definition TIME publishes seven free email newsletters, written and edited by TIME journalists, reaching more than 1.1 million engaged readers. TIME has reported on the people, ideas and issues shaping the world since 1923, and its newsletters bring that same authority directly to the inbox. 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Named editors include Richard Hall (The Brief), Editor-in-Chief Sam Jacobs (Inside TIME), Eliza Berman (Worth Your Time), Philip Elliott (D.C. Brief), Justin Worland (Future Proof) and Harry Booth (In the Loop). Health Matters is written by TIME's health desk. #### How do I sign up for a TIME newsletter? Go to time.com/newsletters, choose the newsletters you want and enter your email address. There is no cost and no subscription requirement. ### Sources * TIME Newsletters: [time.com/newsletters](/c/time-nl-network-2026q3/newsletters?i=dc26347a-34c3-4e12-848d-a20a57772546&cr=time-nl-network-2026q3-v1) ## Video: The Miracle Workers: The Scientists Behind The COVID-19 Vaccine [Watch (HLS stream): The Miracle Workers: The Scientists Behind The COVID-19 Vaccine](https://cdn.jwplayer.com/manifests/BTNvQC2o.m3u8) (5:16)  _Published 2021-12-13. For those of us lucky enough to live in wealthy countries with access to these top-shelf vaccines, it has made all the difference. The miracle workers behind the COVID-19 vaccines are the TIME Heroes of the Year not only because they gave the world a defense against a pathogen, but also because the manner of that astonishing achievement guards more than our health: they channeled their ambitions to the common good, talked to one another and trusted in facts._ by [Akiko Iwasaki](https://time.com/author/akiko-iwasaki/) and [Albert Ko](https://time.com/author/albert-ko/) Jul 19, 2022 11:00 AM UTC by [Akiko Iwasaki](https://time.com/author/akiko-iwasaki/) and [Albert Ko](https://time.com/author/albert-ko/) Jul 19, 2022 11:00 AM UTC Several highly effective vaccines were developed at an unprecedented speed to combat the COVID-19 pandemic. During the phase 3 clinical trials, mRNA vaccines had vaccine efficacy of [94](https://www.nejm.org/doi/full/10.1056/nejmoa2035389)–[95](https://www.nejm.org/doi/full/10.1056/nejmoa2034577)% in preventing symptomatic infections. After the rollout, real-world evidence showed that the mRNA vaccines provided [\~90%](https://www.thelancet.com/journals/laninf/article/PIIS1473-3099%2821%2900472-2/fulltext) effectiveness against infection. Then came the variants. The wave after wave of new variants, with ever-increasing transmissibility and capacity to escape existing immunity, challenge the ability of vaccines to prevent infection and transmission. The effectiveness of a primary series of mRNA vaccines (two doses) to prevent hospitalization and death is also being chipped away by these highly immune-evasive variants. Vaccine-mediated protection became shorter-lived, especially with the emergence of [Omicron variants](https://time.com/6187762/ba-4-ba-5-omicron-subvariants-symptoms-risk/). People look at these data and wonder, what is the point of getting the vaccines if they will not prevent symptomatic infections, and the protection does not last? Well, to expect robust protection from just the primary series of any vaccines is unreasonable—and was always likely to be—but somehow society has placed too high a bar on what is considered an acceptable number of doses for COVID-19 vaccines. Instead, we need to understand that we’re going to be getting boosters in the foreseeable future, and to appreciate their benefits. Vaccines against other infectious diseases are given in multiple doses. Many of our [childhood vaccines](https://www.cdc.gov/vaccines/schedules/hcp/imz/child-adolescent.html) require multiple doses—5 doses for (diphtheria/tetanus/pertussis), 4 doses (Haemophilus influenza type b, pneumococcal conjugate, inactivated poliovirus), or 3 doses (hepatitis B) are all commonly given before the age of 18 years. These doses are required and not considered optional to achieve immunity. In [adulthood](https://vaccinateyourfamily.org/adults/?gclid=EAIaIQobChMIkbOT0IPd-AIVXfLjBx0CxAh-EAAYASAAEgItCPD%5FBwE), many of these vaccines need periodic booster doses to maintain immunity. The influenza virus requires annual vaccination doses for all ages. Yet, people don’t complain about having to get their 60th dose of the influenza vaccine. We should think of COVID-19 vaccines the same way. Why do we need booster doses? The primary series of vaccines kick-starts the immune response by engaging lymphocytes, white blood cells that detect specific features of the pathogen to expand in numbers and become instructed to eliminate the pathogen. Most of these cells disappear over time, except for a small subset of cells that are kept by the body for future use. These “memory cells” are responsible for long-lasting immunity against a given pathogen. What boosters do is stimulate these memory lymphocytes to quickly expand in numbers and to produce even more effective defenders. The booster also selects for B cells that can secrete antibodies that are even better at binding and blocking virus infection and spread. The primary series can be thought of as the high school for lymphocytes, where naïve cells receive basic instructions to learn about the pathogen. Boosters are like a college where lymphocytes are further educated to become more skilled and mature, to fight off future infections. Periodically, these college graduates need refreshers by more booster doses given later in life. This is the case for all vaccines. Booster doses provide the immune system the education it needs to prevent severe diseases from infections. COVID-19 vaccines also need booster doses for the same reasons. We need to educate, maintain, and improve T and B cell responses to prevent severe disease. Boosters provide significant benefits to people who received the primary series in preventing hospitalization and death. In the U.S. in[ April 2022](https://covid.cdc.gov/covid-data-tracker/#rates-by-vaccine-status), people older than 50 years of age who received no vaccine, primary series only (no booster dose), or one booster dose had 38 x, 6 x, or a 4 x higher risk, respectively, of dying from COVID-19 compared to those with two or more booster doses. During the Omicron-predominant period, the booster dose provided protection from hospitalization even in [previously infected](https://www.cdc.gov/mmwr/volumes/71/wr/mm7115e2.htm?s%5Fcid=mm7115e2%5Fw) people, whether older (>65 years of age) or younger (<65 years of age). Among [children and adolescents](https://www.cdc.gov/mmwr/volumes/71/wr/mm7109e3.htm?s%5Fcid=mm7109e3%5Fw), a primary series (two doses) of vaccination was less effective in preventing COVID-19-associated emergency department and urgent care encounters during the Omicron wave compared to the Delta period. Immunity also decreases with time since primary vaccination. No significant protection was detected more than five months after a 2nd vaccine dose among adolescents aged 16–17 years. However, a third booster dose restored vaccine effectiveness to 81% in this age group. There is thus a clear benefit of a booster dose across a broad range of age groups studied to date. Can booster vaccination be improved in the future? Absolutely. We need improved boosters that can provide more durable protection, are effective against variants we encounter moving forward, and do a better job of preventing infection and blocking transmission. For example, booster-induced immune protection wanes within [4-6 months](https://www.cdc.gov/mmwr/volumes/71/wr/mm7107e2.htm?s%5Fcid=mm7107e2%5Fw) during the current Omicron period. We need vaccine strategies that provide more durable protection. Boosters are now [being developed](https://time.com/6196326/covid-19-booster-get-now-or-fall-omicron/) to match the circulating Omicron variant BA.5, which should provide better protection than boosters based on the original strain. However, because of the rapidly mutating nature of SARS-CoV-2, going forward, we will need boosters that can provide coverage against not just the existing but future variants of concern. Boosters that work against a wide range of SARS-CoV-2 variants, now or in the future, as well as against other coronaviruses that may cause future pandemics need to be pursued. Coronaviruses have made the jump from animals to humans multiple times in history which resulted in pandemics. Vaccines that can broadly protect against a wide range of coronaviruses will also prevent future pandemics. In addition, future boosters should be given as [nasal spray vaccines](https://www.nytimes.com/2022/05/16/opinion/covid-nasal-vaccine.html) to provide local mucosal immune protection, capable of reducing infection and transmission at the portal of entry for the virus, and reducing [long COVID risk](https://time.com/6158273/long-covid-19-risk/). Ultimately, we need booster strategies that can be more easily implemented worldwide and have higher acceptance and uptake rates to provide much-needed immune protection for everyone. An over-the-counter nasal spray booster can bring us closer to that goal. Researchers and industry are furiously working on developing next-generation vaccines as they did with our current vaccines, which have saved more than [14 million lives](https://www.thelancet.com/journals/laninf/article/PIIS1473-3099%2822%2900320-6/fulltext) during the pandemic. But for now, take the booster doses you are eligible to keep your immune system educated and up to date so it has the best chance of protecting you from COVID-19 in the upcoming winter season and so we can prevent the enormous loss of life we experienced last winter with more than 300,000 people dying in the U.S. from a disease that can be prevented by current boosters. ## Transcript Kind: captions Language: en I think vaccines are misunderstood, and maybe it's because it seems like magic. That simplicity and the mystery of it is something that ends up creating a lot of skepticism. People are fooled by the speed. Everything that we knew when it was time to design a vaccine for COVID-19, we knew for so long, but the public had just become aware of it. If this would happen two years ago, we would not be ready. Saying that it happened overnight, it took two, three decades, at least. 2021 was the year when so many praised the miracle of vaccine development. In science, there is hardly ever a simple, quick fix. But this was truly a moment of the right fix - a brand new kind of vaccine technology - at exactly the right time. I started out in math, and I moved to biology. And after medical school, I saw one of the first cases of HIV in Tennessee back in 1982. And so the first part of my career was trying to understand the immunology of vaccine-enhanced disease and trying to make vaccines safer. I got interested in science when I was 16 years old. I was hooked on the idea that you could go to work and discover something that no one else in the world knows on any given day. It seems at 16, I thought that maybe I will be a scientist. I was always working with mRNA, I mean for 30 years at least. And I never wanted to develop a vaccine. I wanted to develop it for therapy. When I first came to Penn from the NIH, pure luck hit where I met Kati Karikó over a Xerox machine. And she told me she worked on RNA, and she could help us with our vaccine. Every experiment doesn't work, every hypothesis isn't good. It was a continuous flow of negative feedback. But we saw the potential of the RNA and neither of us would give up. Although mRNA can teach our cells to fight infection, it took doctors Karikó and Weissman 16 years to figure out how to use it safely in a vaccine. First when I made this RNA, actually I did not tell Drew Weissman, my colleague, because I thought that maybe I mixed up something. So I repeated the experiment and we could see that there was no inflammation in human cells. We're both scientists. We're not baseball players who cheer when we hit a homerun. We knew that it had great potential. But what we thought about is what are we going to do with it? Meanwhile, doctors Corbett and Graham spent years unlocking the structural secrets of viruses. One of the really important problems in coronaviruses that had not been solved is really simple. What does the coronavirus really look like to the immune system? And to figure that out, you have to be able to take a really high definition picture of the proteins that are on the surface of the coronavirus. And then do some protein engineering to stabilize the structure. At that moment, you realize that you have almost what is a universal strategy for creating a vaccine for coronaviruses. A mysterious respiratory illness with similarities to SARS has healthcare workers around the world on alert. What we said to each other, all's we need is a sequence and we're ready to go. We can make a vaccine in weeks and get it into people very quickly. The fact that we made a vaccine in 10 months, and has the potential to end this pandemic, will certainly stand out. "Do it mama!" (laughter) Most scientists never get to see a product actually used. And to watch the evening news and see the relief on healthcare providers getting immunized, those were special moments. I also get emotional when I got a letter from an elderly home, and they reported that they received the vaccine. There were like 200 elderly in that home. And nobody died. On social media, when children were going back to visiting their grandparents again. Seeing people reunited in that way, it was a very surreal moment. A surreal moment, and definitely worth celebrating, if only briefly before a return to work. These scientists are now trying to apply their game-changing discoveries to other diseases. Influenza, even cancer. 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