COVID-19 Booster Shots
COVID-19 vaccines are remarkably effective, but their protection can wane over time. That can lead to breakthrough infections in vaccinated people. A booster — an extra dose, taken several months after your last shot — can fortify your immune response to the vaccine.
Currently, everyone over 18 is eligible for a booster. Evidence suggests boosters will be a good way to maintain peak protection, particularly for those who are older, have chronic health conditions, or are at higher risk due to their occupation or where they live.
Read about what vaccine boosters are, how they work, and why they’re being recommended.
Choosing Our Best Shots
Brainstorming
In early January 2020, researchers around the world began designing vaccines to block COVID-19. Within months, there were 125 different vaccine candidates. Nearly all target the virus’s surface spikes, which it needs to infect human cells.
Checking, Testing, Sifting
In test-tube studies, scientists measure how well their vaccines train the immune system to recognize the spiked virus and block it before an infection can take hold. Most won’t make the cut. Promising vaccines are initially tested in animals.
Designing and Conducting Human Clinical Trials
Fred Hutch is working with the National Institutes of Health and others to design and run human clinical trials for five to seven of the most promising vaccine candidates developed by industry partners capable of making millions of doses. These candidates must pass three phases of human testing. Vaccine trials can take five years to design and complete. The goal: to get one or more COVID-19 vaccines ready to go by the end of 2020. In December, two vaccines received emergency use authorization.
Is it safe?
Phase 1 clinical trials show if a vaccine is safe in humans and measure how their immune systems respond to it. They can take more than six months to complete. Researchers monitor patients closely for harmful side effects. While not designed to see if the vaccine can stop infection, such trials may give us early hints. Under fast-track COVID-19 rules, Phase 2 can start long before Phase 1 is done.
Is it working?
Phase 2 trials show whether biological signals of effectiveness show up in volunteers assigned randomly to a vaccine instead of a placebo. Enrolling hundreds, they provide detailed data on the immune response at different dosages in people of different ages and health status. Fast tracked, these trials that normally take a year will be smaller, shorter and run simultaneously with Phase 1 and 3 studies.
Can it do the job?
Up to tens of thousands of people have been enrolled in each Phase 3 trial to see whether a vaccine can protect individuals in a community against COVID-19. These studies must be large enough to prove that the vaccine reduces the risk of infection or serious illness. In the U.S., two vaccine candidates were declared successes by the end of 2020. Researchers then will see how these compares to those that follow.
Manufacturing Enough Vaccine to Cover the World
Making enough vaccine to protect the world from COVID-19 will require an astonishing scale-up of global manufacturing. U.S. experts say 4.4 billion doses are needed to cover adults worldwide, a figure that would jump if shots are needed for kids. No one pharmaceutical company can meet that demand. Hence, current strategy supports development of many different vaccine types and building factories in advance, in hopes of approval. The U.S. has already bought vaccines “at risk” so that those doses — now in production — could be ready immediately upon approval. Bill Gates pledged to help fund factories for seven different vaccine candidates, knowing not all will succeed. Yet factories alone won’t work unless their supply lines for biological ingredients, immune-boosting adjuvants, and even the specialized glass vials and rubber stoppers to hold vaccines are stocked. The Trump administration initiative to have 300 million doses ready by January 2021 was called “Operation Warp Speed.”
“It'll be a few billion dollars we'll waste on manufacturing for the constructs that don't get picked because something else is better. But a few billion in this … where there's trillions of dollars being lost economically — it is worth it.”
– Bill Gates, Chairman, Bill & Melinda Gates Foundation
Scaling Up Distribution
Shipping enough vaccines to cover 200 million adults in the United States, let alone to billions of others around the globe, is also massive undertaking and logistical challenge. Scale-up of distribution must consider that different vaccines may be more appropriate for one part of the world than others. For example, vaccines that require refrigeration may not work for developing countries in hot climates. Where health care clinics are hard for people to reach, single-dose vaccines will be better than those requiring two. With much of world trade constrained by COVID-19 border closings, transport of vaccines must clear regulatory hurdles and compete for cargo space. The sheer volume of shipments requiring careful handling will be a challenge for planes, trucks and even bicycles needed to get COVID-19 vaccines to the right places.
Delivering COVID-19 Vaccines to People
From the moment the idea for a COVID-19 vaccine formed in researchers' minds, the goal has been to deliver it into the arms of billions. It is a difficult journey that typically takes a decade or more, but given this crisis, those time scales have been compressed. With the first vaccine doses limited, the question has been, who gets the vaccine first? Policymakers ensured that health care workers and some particularly vulnerable populations, such as nursing home residents, were among the first to be vaccinated. They also have faced some difficult choices: Which essential workers should be first when supplies are limited? Are highly paid executives more essential than grocery store clerks? Are meat packers and farm workers more essential than waiters and cooks in restaurants? What are the policies in place to ensure that access to vaccines does not divide along racial, ethnic or international lines?