“There are too many unknowns about that, while the vaccine is known — that’s my caveat,” said Dr. Peter Chin-Hong, an infectious disease expert at the University of California, San Francisco. “Certainly I wouldn’t put all my eggs in the previous infection basket, natural immunity.”
As with the protection offered by vaccines, immunity against natural infection can weaken over time, leaving children susceptible to reinfection. “I’d like to know when that infection was,” said Dr. Chin-Hong. “If it was a year or so ago, I’d be concerned about waning immunity.”
What you need to know about Covid-19 booster shots
Who is eligible for a booster shot?
The FDA has authorized booster shots for millions of recipients of the Pfizer-BioNTech, Moderna and Johnson & Johnson vaccines. Recipients of Pfizer and Moderna who are eligible for a booster include people 65 and older and younger adults at high risk of severe Covid-19 due to medical conditions or where they work. Eligible Pfizer and Moderna recipients can receive a booster at least six months after their second dose. All Johnson & Johnson recipients are eligible for a second injection at least two months after the first.
Can I exchange Covid vaccines for a booster?
Yes. The FDA has updated its authorizations to allow medical providers to incentivize people with a different vaccine than the one they were initially given, a strategy known as “mix and match.” Whether you’ve been given Moderna, Johnson & Johnson, or Pfizer-BioNTech, you can get a booster from any other vaccine. Regulators have not recommended one vaccine over another as a booster. They have also kept quiet about whether it is preferable to stick with the same vaccine if possible.
What underlying medical conditions are eligible for a booster injection?
The CDC has said the conditions that qualify a person for a booster injection are: hypertension and heart disease; diabetes or obesity; cancer or blood disorders; weakened immune system; chronic lung, kidney, or liver disease; dementia and certain disabilities. Pregnant women and (ex-)smokers are also eligible.
Which professions are eligible for boosters?
The FDA approved boosters for workers whose jobs put them at high risk of exposure to potentially infectious people. The CDC says that group includes: medical workers; education workers; food and agricultural workers; factory workers; corrections employees; US Postal Service workers; employees in public transport; grocery store workers.
Can I get a flu shot at the same time as a Covid vaccine or booster vaccination?
Yes. The CDC says the Covid vaccine can be administered without regard to the timing of other vaccines, and many pharmacy sites allow people to schedule a flu shot at the same time as a booster dose.
In adults, natural immunity generally “seems to hold up well,” said Dr. Bhattacharya.
But it’s unclear whether the protection seen in adults extends to children, in part because most children have milder symptoms than adults and may not have built up a full defense against the virus.
Natural immunity in children may also not withstand variants. Several studies have shown that just one dose of the vaccine in a previously infected adult can enhance protection, even against variants such as Beta and Delta.
“I suspect that will be the case with children as well,” said Dr. hensley.
Vaccination should also reduce the chance that a re-infected child will pass the virus on to others who may be susceptible to serious illness. “If someone in your household is extremely vulnerable, the consequences are pretty bad,” said Dr. Bhattacharya.
I am concerned about side effects. Is the vaccine safe?
All the evidence to date indicates that the vaccines are much safer than a Covid attack, even for children.
For example, although the vaccines have been linked to the rare risk of myocarditis, inflammation of the heart, in young men, most of them quickly resolved the symptoms. Covid is much more likely to cause myocarditis, and a much more severe version.