new variants put mass immunity in check

posted on 09/11/2021 06:00

Street in London: the delta strain, discovered in India, is 60% more contagious than alpha, first recorded in the UK - (credit: Niklas Halle'n/AFP - 7/6/21)

Street in London: the delta strain, discovered in India, is 60% more contagious than alpha, first recorded in the UK – (credit: Niklas Halle’n/AFP – 7/6/21)

Authorities at the World Health Organization (WHO) are pessimistic about the possibility of reaching the so-called herd immunity against covid-19 only with the application of vaccines. Until then, it was believed that, if 70% of the world’s population were immunized, it would be possible to work with the idea of ​​having the spread of the virus under control. Yesterday, however, Hans Kluge, medical specialist in public health and WHO regional director for Europe, said that the new variants could be calling into question the scenario that a high rate of vaccination would alone stop the current health crisis.

The statement was made at a press conference at which experts from the United Nations agency reported that the emergence of new strains of Sars-CoV-2, such as delta, are increasing the transmission power of the virus and, consequently, reducing the chances of achieving collective immunity. In this scenario, for Hans Kluge, the probability that the new coronavirus remains an endemic disease is increasing.

For this reason, he asked world authorities and officials in the area to create more effective vaccination strategies, especially with regard to booster doses. “If we consider that covid-19 will continue to mutate and remain among us, like the flu, then we must predict how to progressively adapt our vaccination strategy against endemic transmission and gain more valuable knowledge about the impact of additional doses,” he said. .

In May, the WHO regional director declared that the pandemic would end when we reached “a minimum vaccination coverage of 70%” of the world’s population. Yesterday, when asked if he kept what he said, Kluge replied that the new variants, especially the more contagious ones, have changed the situation. He explained that, before, although the delta strain, first detected in India, already existed, “there was no similar emergence of more transmissible and more viral variants”. “This brings us to the point that the essential objective of vaccination is, above all, to avoid the severe forms of the disease and mortality”, he highlighted.

The delta variant — currently dominant in almost all countries hit by the covid-19 pandemic — is estimated to be 60% more contagious than the alpha, initially recorded in the UK, and twice as much as the strain that started the worldwide outbreak. The more contagious a pathogen, the higher the rate of people who need to be immunized to achieve collective immunity and stop the epidemic, and theoretically immunity can be achieved with vaccines or by being infected.

According to epidemiologists, as unrealistic as it may seem to achieve collective immunity with protective drugs alone, they are still essential to stop the pandemic. Immunization also remains paramount “to reduce the pressure on our health systems, which desperately need to treat diseases other than covid-19,” added Kluge.


The UN agency links the debate to criticism of the application of booster doses against covid — a strategy adopted by several countries. From a scientific point of view, there is a consensus on the need to protect people with a vulnerable immune system, such as the immunosuppressed and the elderly. But WHO criticizes what it classifies as “widespread use” of the measure.

“At the moment, we don’t want widespread use of booster shots for people in good health who are fully vaccinated. I will not remain silent when companies and countries that control the world’s supply of vaccines think that the world’s poor should be content with leftovers,” said Tedros Adhanom Ghebreyesus, director general of the organisation, on Wednesday. At the time, he also asked for the moratorium on booster doses to be extended to at least until the end of this year, so that each country can vaccinate at least 40% of its population.

bet on new drug

US researchers are betting on a drug used to treat gout as a new therapy against covid-19. They observed positive results when using the drug in human cells and animals infected by the new coronavirus, as well as other similar pathogens. The work data were presented in the latest edition of the specialized magazine Scientific Reports.

In the article, the authors report that the search for treatments for covid-19 is extremely important, considering the limited available therapies. “There really isn’t a completely effective alternative to safely combat these viruses,” emphasizes in a statement, Ralph Tripp, lead author of the study and a professor at the University of Georgia School of Veterinary Medicine.

Tripp and colleagues chose to assess the curative power of probenecid, which had shown remarkable antiviral properties in previous studies. The drug was tested in human cells and in mice infected with Sars-CoV-2, influenza (flu) and respiratory syncytial (common in newborn children) viruses. Results were positive in all analyses.

“This drug reduced the amount of viruses, and this is something that can help us to treat the disease (covid). Another advantage is that this medicine is safe for humans because it has been widely used for over 40 years”, celebrates Tripp. The next stage of the study will be to assess the drug’s power in clinical analyzes with volunteers.