Some people are skipping their second dose of the Pfizer-BioNTech or Moderna coronavirus vaccines, but experts emphasize that it is crucial for people to get both shots for the most protection.
According to a New York Times review of data from the Centers for Disease Control and Prevention, nearly 8% of people who received their first dose had not returned for a second.
"It really is prudent to get both doses," said Dr. Luke Davis, an associate professor of epidemiology at the Yale School of Public Health in New Haven, Connecticut, noting that the second dose takes you to the "next level" of protection.
Why do I have to get both doses?
"We know that you're going to have a much stronger, more potent response to the vaccine when you get that second dose," Davis said. "With the first dose, you're just priming the immune system, and when the second dose comes in, the immune system has a chance to be further trained."
Davis also highlighted preliminary research that tests the real-world effectiveness of the coronavirus vaccines: Reports from the CDC show that people who received both doses of the vaccine were about 90% protected three months after being vaccinated. People who only had the first dose were about 80% protected.
Davis said that the difference might become more pronounced as time went on.
"For example, if immunity wanes or kind off wears off, as some people have predicted, after a number of months, you would expect that it would last longer if you get two doses," Davis said.
Summer McGee, dean of the School of Health Sciences at the University of New Haven, said that people should not be deterred by the potential inconvenience of getting a second dose, calling it "absolutely critical."
"The second dose really gives you that full immunity boost ... You really want to get that second dose to get the maximum amount of protection," she said.
Side effects after the second dose:
Some have indicated that they're worried about potential side effects from the second dose of the vaccine, which can include short-term symptoms like fevers, chills, fatigue and arm pain. Davis and McGee both emphasized that these side effects are brief and should not discourage anyone from getting vaccinated.
"What you're seeing is that your body has already recognized the vaccine particles and the genetic code before (from the first dose), and now it knows to respond even more aggressively when you get that second dose," McGee said. "It's your body really giving you that full immune response, and so that's why people can experience more severe side effects the second time around."
While it varies from person to person, the side effects are usually quick, emerging within a few hours of vaccination. The longest most side effects seem to appear is 24 hours after receiving the second dose, according to McGee, and side effects don't usually last more than 24 hours after emerging.
"I think most people find that after 24 hours, they're not having those symptoms anymore," Davis said.
McGee said that while side effects might be unpleasant in the moment, people should consider them a "good thing."
"It's a sign that your immune system is responding," she said. If you have no side effects, don't worry: Experts say that whether or not you have a reaction, the vaccine is still effective.
If you want to head off any potential side effects, McGee recommends being hydrated and well nourished before your vaccine appointment. People should avoid taking any over-the-counter painkillers before their appointment, but can take medication after being vaccinated.
What if I contract COVID-19 between doses?
It is possible to contract the coronavirus after being fully vaccinated, though the number of documented breakthrough cases is very small. It's also possible to contract the virus between doses, and the CDC has shared guidance on what people should do if they get sick between their first and second dose of the coronavirus vaccine.
"If you get COVID between the first and second doses, the CDC recommends allowing symptoms to resolve and completing the 10-day isolation period, then getting the second dose as close to the standard 3- or 4-week interval as possible, and ideally within 6 weeks of the first dose," said Davis. "Those receiving monoclonal antibody treatment or convalescent plasma for COVID are advised to wait 90 days, because these therapies could prevent the vaccine from working properly."