Has the Virus Infected Huge Numbers of Younger Children?


“There are too many unknowns on that, whereas the vaccine is known — that’s my caution,” said Dr. Peter Chin-Hong, an infectious disease expert at the University of California, San Francisco. “Certainly, I wouldn’t put all my eggs into the previous infection, natural immunity basket.”

As with the protection conferred by vaccines, immunity from natural infection may weaken over time, leaving children susceptible to reinfection. “I’d be interested to know when that infection was,” Dr. Chin-Hong said. “If it was a year or so ago, then I would worry about waning immunity.”

What to Know About Covid-19 Booster Shots

The F.D.A. has authorized booster shots for millions of recipients of the Pfizer-BioNTech, Moderna and Johnson & Johnson vaccines. Pfizer and Moderna recipients who are eligible for a booster include people 65 and older, and younger adults at high risk of severe Covid-19 because of medical conditions or where they work. Eligible Pfizer and Moderna recipients can get a booster at least six months after their second dose. All Johnson & Johnson recipients will be eligible for a second shot at least two months after the first.

Yes. The F.D.A. has updated its authorizations to allow medical providers to boost people with a different vaccine than the one they initially received, a strategy known as “mix and match.” Whether you received Moderna, Johnson & Johnson or Pfizer-BioNTech, you may receive a booster of any other vaccine. Regulators have not recommended any one vaccine over another as a booster. They have also remained silent on whether it is preferable to stick with the same vaccine when possible.

The C.D.C. has said the conditions that qualify a person for a booster shot include: 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 current and former smokers are also eligible.

The F.D.A. authorized boosters for workers whose jobs put them at high risk of exposure to potentially infectious people. The C.D.C. says that group includes: emergency medical workers; education workers; food and agriculture workers; manufacturing workers; corrections workers; U.S. Postal Service workers; public transit workers; grocery store workers.

Yes. The C.D.C. says the Covid vaccine may be administered without regard to the timing of other vaccines, and many pharmacy sites are allowing people to schedule a flu shot at the same time as a booster dose.

In adults, natural immunity generally “seems to be holding up well,” Dr. Bhattacharya said.

But it’s unclear whether the protection seen in adults extends to children, in part because most children tend to have milder symptoms than adults and may not have mounted a full-throttled defense against the virus.

Natural immunity in children also may not hold up against variants. Several studies have shown that just one dose of the vaccine in a previously infected adult can turbocharge protection, even against variants like Beta and Delta.

“I suspect that will be the case with kids, as well,” Dr. Hensley said.

Vaccination should also lower the chances of a reinfected child passing the virus to others who may be susceptible to severe illness. “If someone in your household is extremely vulnerable, then the consequences of that are pretty bad,” Dr. Bhattacharya said.

All of the evidence so far indicates that the vaccines are far safer than a bout of Covid, even for children.

For example, although the vaccines have been associated with the rare chance of myocarditis, inflammation of the heart, in young men, the symptoms have quickly resolved in most of them. Covid is much more likely to cause myocarditis, and a much more severe version.



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