LumberJack

Still gotta social distance and wear a mask after vaccination.

"Let's start with the first question, about whether people who are vaccinated can still spread the disease. Marion Pepper, an immunologist at the University of Washington, says that's not just an open question for this vaccine, but for vaccines in general."I think it's hard to say because we're constantly being bombarded by different pathogens and we don't know when your immune system is responding," she says. We may have infections that don't make us sick, so we never know about them. But we could be spreading disease.

When a person is infected – or inoculated with a vaccine – the immune system gears up to produce antibodies that specifically target the virus. Over time, those antibodies naturally wane. But the immune system still holds a memory of the virus, and if it ever shows up again, cells spring into action and start to gear up a new batch of antibodies. However, that process can take three to five days.

In the meantime, a virus can potentially start to replicate in the body.

"It's a bit of a race between the immune system and the virus," says Dr. Michel Nussenzweig, a Howard Hughes Medical Institute investigator at the Rockefeller University.

If the immune response kicks in quickly, little virus would be produced. Your ability to spread disease "is really a function of how much virus you're producing," Nussenzweig says.

It seems likely a person's immune system will win that arms race, but scientists don't have the data yet to say that with confidence. That's why people who have been vaccinated are still supposed to wear a mask and take other precautions – until that gets sorted out.

Another wild card here is that your lungs and nasal passages contain a population of so-called T cells, which are primed to identify cells that have been infected with a virus. This type of T cell is much harder to study since it stays inside tissues, so scientists studying blood samples don't end up seeing it.

Since these T cells are primed to react immediately, they might also help bridge the gap between the time you get infected and the time that your immune system can mount a full response with antibodies.

"In influenza, those T cells that are embedded in the tissue can have a dramatic effect of limiting the infection," says Stephen Jameson, an immunologist at the University of Minnesota Medical School. But whether they perform as well in COVID-19, "we don't really know enough yet," he says."

3 Questions And The Emerging Answers About COVID-19 Vaccine Protection