Sebastián De Toma joined Pfizer’s clinical trial last year, getting his injections in August and September. The Argentine journalist is still not sure whether he received the real covid-19 vaccine or the placebo, but on Sunday, January 31, doctors in the trial called him with a new offer.
Would De Toma be prepared to undergo a series of nasal swabs to regularly test for the virus? He says doctors offered to send Cabify (a Spanish ridesharing service) to take him to the military hospital in Buenos Aires. “They’ll dab me on the go, through the car window, and that’s it,” De Toma says.
The additional coronavirus tests, offered to some volunteers in Argentina and the United States, are part of a Pfizer plan to help answer an unknown key: how often vaccinated people develop asymptomatic coronavirus infections, and if they can still spread the virus despite getting hit.
Whether or not vaccines stop the “continuous transmission” of the virus will likely be a critical variable in determining how the pandemic unfolds and how long life will return to normal. Right now, researchers say, their best guess is that vaccines will reduce transmission but may not prevent it entirely.
“We don’t know, but it’s an important question because the answer will influence the wearing of the mask; it will influence behavior; it is linked to the comfort of going to restaurants and the cinema and to the overall benefit that can be expected from vaccines ”, states Lawrence corey, who heads the operations of the Covid-19 Prevention Network, which has conducted several vaccine trials in the United States.
The mystery of the silent spreader
“There are three things a vaccine can do: stop you from completely contracting the disease, stop transmission, and stop symptoms,” says Jeffrey Shaman, a public health researcher at Columbia University. A perfect vaccine would create what is called “sterilizing” immunity, which means that the virus cannot take hold in your body at all. However, some vaccinations allow low-level infections that people’s immune systems fight off without any symptoms. Their bodies still accumulate a certain amount of the virus, which they may be able to pass on to others.
The reason we don’t know how well vaccines stop this transmission is because it’s expensive and complicated to measure. When companies like Pfizer, Novavax, Moderna Therapeutics and others launched large studies of their new covid-19 vaccines last year, they were testing whether vaccines could prevent people who had contracted the disease from getting sick. or die. The results in this regard are impressive: virtually no vaccinated person ends up in an intensive care unit on a ventilator.