The World Health Organization points out that a person infected by the virus can develop “strong immunity” and that new studies indicate that such protection is capable of lasting for months. But the organization also makes it clear that there is still no way to give specific numbers and no guarantees that reinfection can be avoided.
At the beginning of the pandemic, some studies indicated that, even if infected, a person could develop immunity of just a few months. Re-infection cases have also been confirmed.
Now, the world agency believes that the numbers are sufficient to indicate that, even with some cases of reinfection, the virus generates a “strong immunity response”. Mike Ryan, WHO’s director of operations, makes it clear that, like other viruses, immunity is not permanent. “We don’t know for how long. But immunity is strong,” he said.
According to him, the WHO established a committee especially dedicated to studying this aspect and assessing whether, in the case of contamination on a second occasion, the reason was the drop in immunity or if the person did not develop full immunity.
Ryan still calls for people, even though they have overcome the virus, to show solidarity and continue to circulate with masks. Firstly, according to him, because there is still an eventual and theoretical risk of contamination. But, above all, not to create the perception in a group that some members do not care and can enter indoors without masks.
Ryan also insisted that WHO will not tolerate the idea that, faced with 35 million cases, it would be time to abandon the fight and let the virus circulate. “I will not admit sacrificing the elderly,” he said. For him, when fighting transmission, governments gain time to care for those who are sick and still allow them to prepare and study the disease.
Still, studies have indicated that the virus has undergone a slow mutation, which allows it to be studied more intensively.
For WHO, there are no signs that the virus is getting softer. But the drop in the death rate in some countries is a sign that systems are better prepared to deal with cases.
“Mortality is decreasing. But it is not due to the virus. It is due to a better response,” said Maria Van Kerkhove, WHO technical director.
Transmission by air
The organization also admits that the studies broaden the thesis that the covid-19 virus can be transmitted by particles that are suspended in the air, released by an infected person when breathing, speaking or singing.
On Wednesday, the main technicians of the organization indicated that the most likely thesis, after months of the pandemic, is that the virus can be transmitted by a series of methods. One is contact, including on surfaces, or by droplets expelled during coughing. But the organization recognizes that aerosol transmission is likely.
“All modes of transmission can occur,” admits Mike Ryan.
The subject had already led a group of 239 scientists to make a warning in this regard. They called on WHO and governments to recognize that aerosol transmission was a possibility, which would prompt authorities to take more drastic measures.
Earlier this week, a letter published by Science magazine warned of the need to take steps to curb such transmission routes. This includes wearing masks and increasing ventilation in certain locations.
“There is overwhelming evidence that inhaling SARS-CoV-2 represents an important route of transmission for Covid-19,” write the scientists, led by Kimberly Prather, of the University of California, San Diego. For the group, it is much more likely to inhale aerosols than a drop, so attention should be focused on protecting against airborne transmission. “
In the USA, the Center for Disease Control and Prevention (CDC) recently pointed in the same direction.
At WHO, the perception is that such a path of the virus is a reality. “We are certainly seeing this. It is a mix of paths. It is a virus that can exploit through multiple transmission paths,” said Ryan. For him, certain situations of transmission are difficult to explain. “We would have to conclude that it must be aerosolized,” said Ryan.