The chances of getting sick with covid drop dramatically after three weeks from the first dose of the vaccines: confirmation comes from the latest report on positivity after vaccination published by the National Statistics Office (ONS) of the United Kingdom. Based on the analysis, carried out on adults vaccinated by May 31 with at least one dose of Pfizer or AstraZeneca, in rare cases of post-vaccine infection, obvious symptoms or a high viral load are less likely to develop.
The trend of the curve. The data show an initial increased risk of infection after the first dose that peaks at 16 days post-vaccine; at this point the risk of contagion collapses, decreasing sharply around one month after the first dose, and then continues to decrease, but more gradually.
The initial increase in infections in the very first days after vaccination had already been detected in other studies and may be due to: an undetected contagion before vaccination, the choice to be vaccinated because we have become aware of close positive contacts, the proximity to asymptomatic positive people in vaccination centers or a general relaxation of prevention measures (distancing and masks) after receiving the first dose.
Positive after the vaccine? It can happen, but it’s very rare. Reinfections after vaccines are extremely rare. Out of 297,493 vaccinated with the first dose, only 0.5% developed a new infection. And of 210,918 adults who received both doses of the vaccines, only 0.1% subsequently tested positive for the new coronavirus again. The characteristics related to a greater risk of new positivity after the vaccine are being under 40 years of age, working close to patients in healthcare settings, living in large families or in precarious economic conditions.
The unvaccinated are at risk. And while the United Kingdom sees the number of infections due to the Delta variant rise, comments Paul Elliott, scientist at Imperial College London and co-author of the study: “I think we can find comfort in the fact that, when we look at the details, we sees really good protection in old age, a range where virtually everyone has been double-shot vaccinated. And in the younger groups under 65 where a smaller percentage have been vaccinated or had double doses, most infections are occurring in the unvaccinated. ‘