A Hong Kong study shows that the double dose of CoronaVac does not produce enough antibodies. Data provided by the pharmaceutical company Sinovac argues that the booster improves protection. Disappointing results also from Sinopharm
A new study by researchers from the University of Hong Kong found that people who received two doses of a Covid-19 vaccine made by the Chinese pharmaceutical company Sinovac (vaccine CoronaVac a virus inactivated) were unable to neutralize the new highly infectious variant Omicron.
The data of the clinical studies that led to the use of the preparation in various countries reported an efficacy of 50% in the study carried out in Brazil and 83% in the one carried out in Turkey and subsequent investigations have shown that the antibodies decay already after six months from the end of the vaccination cycle. Now research in the Hong Kong laboratory has specifically investigated the Omicron variant.
The investigation was conducted on 25 vaccinated individuals: scientists found that none of the sera of the study participants was able to combat the Omicron variant, highly contagious. Most likely they will be necessary boosters to improve protection.
Sinovac’s statements
It is not entirely clear whether a third dose of the Chinese vaccine could actually improve the situation: the pharmaceutical company Sinovac, while admitting that two doses are ineffective against Omicron, said that three doses could prevent infection and disclosed the tests carried out in the company. From the data it appears that 7 out of 20 people, 35% who received double doses of Sinovac showed sufficient antibodies to neutralize Omicron. The picture improved slightly with three doses: the laboratory results show that 45 out of 48 people who received the booster developed sufficient antibodies to neutralize Omicron. The details of the study carried out by the pharmaceutical company have not been disclosed and are not published.
Mediated immunity
The studies are preliminary and antibody levels do not provide a complete picture of a person’s immune response because in the real world, too much is involved.cell-mediated immunity, which in most laboratory tests is not studied because very sophisticated equipment is required.
The spread of Coronavac in the world
However, the absence of neutralizing antibodies against Omicron among those vaccinated with Coronavac can represent a big problem for China and for other countries where the drug has been widely used including Brazil, Mexico, Chile, many Asian countries and South Africa (precisely from where the new Omicron variant was developed): 2.3 billion people. Other studies have also found disappointing results with Sinopharm, (also used in the United Arab Emirates) the other important vaccine widespread in China that would show no antibody activity in most of the subjects analyzed. If the research results are confirmed, China would face a major problem with the new variant. So far the country has protected the population with massive lockdowns and border closures, as well as having vaccinated 1.4 billion people, almost all with Coronavac.
Natural immunity
Among other countries, such as Brazil and Indonesia, which use Coronavac, the previous waves of infection they would have conferred some natural immunity which will help Omicron have no major impact, he said Benjamin Cowling, professor of epidemiology at the University of Hong Kong interviewed by Bloomberg. But the populations of mainland China and Hong Kong who have never experienced large-scale infections are in fact vulnerable. So far, China has intercepted two cases of Omicron among travelers returning to the country, one of which was discovered more than two weeks after entering China and could therefore have spread the very contagious virus to numerous other people.
December 16, 2021 (change December 16, 2021 | 18:57)
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