Vaccine: It is with great satisfaction and euphoria that we have received the news of the acceleration of vaccination in Brazil. There is a glimpse that we will finally be able to get rid of the evil of the pandemic that directly interferes with everyday life. But is it really?
An article in the scientific journal Nature (one of the most respected) carries the translated title: “Five reasons why‘ herd immunity ‘is probably impossible ”. One of the main reasons is that “herd immunity” is not a finish line, but a temporary and dynamic state, which will suffer constant threats from the new variants and from the natural drop in immunity (generated by infection or by the vaccine) that occurs when over time. And yet, there is still no guarantee that vaccines will be able to induce “herd immunity” (even if temporarily) as the effectiveness of preventing transmission is still unclear.
What are the alternatives?
So there is no way out? Of course there is. Vietnam has 0.05% of the population vaccinated. New Zealand, 1.4%. South Korea, 1.7%. Australia, 2.6%. And they are not in a hurry to vaccinate. That’s because they are countries that have found sustainable ways to control viral circulation. In addition to the well-known measures for wearing masks, physical distance and hand hygiene, these countries have taken two key measures to avoid the dreaded lockdowns: real mass testing and border control.
Mass testing is not simply about increasing the number of tests. This is a consequence. The secret is to expand the test indication. Amplifying tests aiming only at diagnosis of suspicious cases have very little effect on transmissibility. Extending the indication, including testing on confirmed case contacts and even with regular testing on asymptomatic high-risk patients, makes the ability to identify transmitters more quickly, with a reduction in transmissibility. For these purposes, rapid antigen tests, even if less sensitive for diagnostic purposes, allow for the expansion of the indication and the speed of the result. In the end, they have greater population sensitivity and are more suitable for reducing transmissibility.
Border control is done through quarantine and tests on 100% of individuals arriving from other countries. Recalling that the variant P.1, from Amazonas, was identified in Japan, through testing on Brazilian travelers who left Manaus.
Responding to the title of the article: according to the Institute for Health Metrics and Evaluation, Vietnam has an estimated 0.02 cases / million inhabitants, without vaccination. It is estimated that Brazil has 120 cases / million inhabitants, that is, there is a 6000 greater chance of having the virus in Brazil compared to Vietnam.
Considering that the Coronavac and Aztrazeneca vaccines reduce the chances of symptomatic infection by 50.4% and 62% respectively, the benefit generated by the vaccine is infinitely less than the increased risk of exposure that currently exists in Brazil. Before fighting for a vaccine, we should be indignant that we are not in the situation that Vietnam is in.