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When there is no cure, metrics such as the prevalence of infection and immunity in a population become important.
That’s why the results of the New York study of 3,000 people chosen at random for an antibody test that were announced Thursday are being studied worldwide.
With the caveat that there are still question marks about the first phase of antibody testing for Covid-19, it turns out that there have been problems with the first phase of antibody testing for almost anything, including HIV-AIDS, according to the study 21.2% of the sample in New York City tested positive.
New York City may be an atypical case given its population density (the corresponding proportion for the state, in the same study, was 14%), but the study, which must be validated in a larger population, is very significant: means the extent of infection is much greater than previously measured; It also means that death rates are much lower (in fact, much, much lower).
It has long been said that the number of people infected with the Sars-CoV-2 virus, which causes Covid-19, is actually higher than reported, one that has gained currency after confirmation that many people infected they are asymptomatic and 97% of the cases (according to worldometers.info) are mild. In New York City, for example, this would mean that about 1.8 million people have been infected, did not know it, and did not get sick or fight a disease that was too brief.
A similar study in France stated that 6% of the French population was infected.
The New York study is important because it shows that antibody tests can be used to measure the prevalence of the disease in a population. Some countries also want to use these tests to decide how and when to open: a person with antibodies should, in principle, be immune to the disease and return to work safely. Experts are not so sure because not enough is known about Covid-19 to assess how long people with antibodies will remain immune to the disease.
Such tests, which are continually being refined and improved, will also help measure whether countries achieve collective immunity. This is the proportion of the population that needs to be infected with the virus (and therefore become immune, at least in theory) to ensure that the virus does not easily jump from person to person. Experts put the number at 60-65%.
Studies from France and New York show that it will be a while before that number can be reached.
Sars-CoV-2 is clearly an irritating virus: it is highly infectious, has not mutated and weakened, and became extinct like many other viruses before, and remains uncured. Every promising line of prophylaxis and treatment has ended in failure. The last one is Gilead’s failed Ebola drug remdesivir. The Guardian reported that the drug did not work in its “first complete trial.” A previous trial in China, the report adds, yielded a similar result.
In addition to its vexatious nature, it is the discovery that, although it infects more than one population than initially thought, the virus does not infect enough to cause collective immunity.
Now everyone is pinning their hopes on a vaccine trial that started Thursday in Oxford. The vaccine, which uses a weak strain of a virus that causes chimpanzees to catch a cold, has sparked excitement after one of the scientists involved in its development, Sarah Gilbert of the Jenner Institute, told the media last week that she was 80% sure that vaccine success. Everyone expects her to be right.
