The plan to give a booster to every adult eight months after their last dose has come under criticism from some scientists who say the data isn’t there yet to support such an effort — especially as global inequities in vaccine availability persist.
Many questions remain, and official guidance is not yet available. But here is what we know so far.
Who should get extra shots now?
The Centers for Disease Control and Prevention said some people who are moderately to severely immunocompromised may not have built up enough protection with their first vaccinations. That includes people who have been getting treatment for tumors or blood cancers, organ transplant recipients, those with advanced or untreated HIV infection, and others who are taking drugs that suppress the immune system.
The agency recommended that those individuals get a third dose of the Pfizer or Moderna vaccines at least 28 days after finishing the original two-shot series. The CDC refers to this as a third dose rather than a booster, which refers to an additional dose for someone who built enough protection initially but for whom the protection has waned over time.
According to the CDC, there is not enough data yet to say if immunocompromised people who were vaccinated with the Johnson & Johnson one-dose shot should get another dose.
What does that mean for travel?
Amesh Adalja, senior scholar at Johns Hopkins Center for Health Security, said those who are immunosuppressed should get the third dose right away no matter what, but travel makes it even more urgent.
“It is important to get that third dose especially if you’re going to a place that has a high prevalence of the disease,” he said.
Patrick Kenney, an infectious-disease specialist at Cleveland Clinic Weston Hospital in Florida, said in an email that he would recommend vulnerable populations wait about two weeks after the additional shot before traveling.
“Of course, other safety precautions such as mask-wearing, proper handwashing and social distancing would still be recommended while traveling to avoid exposure,” he said.
For this group of people, travel could be too dangerous to risk now, said David Freedman, professor emeritus of infectious diseases at the University of Alabama at Birmingham.
"Compromised people should not travel to most countries regardless of vaccination status," he said.
What about everyone else?
The CDC is not yet recommending boosters or additional shots for anyone beyond those at the highest risk and has not offered guidance on boosters and travel. The Biden administration’s plan is awaiting some steps: approval for boosters by the Food and Drug Administration and CDC recommendations. Biden’s decision was informed by advisers from both federal agencies.
Adalja said fully vaccinated people will have some risk of breakthrough infection, the vast majority of which will be mild. He said society needs to decide whether the goal needs to be stopping every case of covid-19 or just the serious ones.
“It’s not a foregone conclusion that the healthy population needs boosters at six months or eight months,” he said. “That really hasn’t been vetted completely, and I think it’s important for the process to occur where they’re actually presenting the data to drive that decision.”
How could this affect travel plans in the future?
It’s not clear what the CDC will say about whether vaccinated people should get boosters before travel. For now, the guidance for fully vaccinated travelers refers to those who are two weeks past their second shot.
Freedman said a traveler should follow whatever is recommended for their own situation before going on a trip — once that recommendation is known.
Kenney said his advice to someone who was traveling to an area of high covid-19 transmission would be to get a booster after they reach the eighth-month mark after their first vaccine series and then wait to travel for another two weeks.
Will vaccine mandates eventually include a third dose?
Adalja said he does not believe there’s strong data for such policies that consider vaccinations good enough for only about nine months.
It is hard to say whether boosters will be added on to existing vaccine mandates, Kenney said. But he said travel and other parts of life will be safer once doses are available to the entire world.
“There is so much inequity globally with vaccines that we need to strive to get resource-poor countries access to vaccines so that we can lower the global transmission of this virus,” he said in an email. “It will be then that we can see how life in the post-COVID-19 pandemic world will be and what the vaccine requirements for travel and businesses will entail.”