Experts insist that the biologicals “are not bad,” they just need to be optimized for changes to SARS-CoV-2.
According to experts, the efficacy of Chinese Covid-19 vaccines CoronaVac and Sinopharm −which have been crucial to combating the pandemic and have been administered in different countries around the world− diminishes quickly and the protection afforded to the elderly is limited.
In fact, the Strategic Advisory Group of Experts (SAGE) on Immunization has recommended that people over the age of 60 who received the Sinovac and Sinopharm vaccines should also get a third dose, although the use of other vaccines could also be considered depending on supply and access.
This advisory group to the World Health Organization (WHO) said that immunocompromised patients should be offered an additional dose of all coronavirus vaccines approved by the WHO.
“Since these individuals are less likely to respond adequately to vaccination following a standard primary vaccine series and are at high risk of severe Covid-19 disease.”
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The Chinese CoronaVac vaccine, which is produced by Beijing company Sinovac from the inactivated virus, was approved for use in Mexico on February 9 of this year, although it does not have an ongoing clinical trial in the country.
Despite this situation, Gagandeep Kang, a virologist at the Christian Medical College in Vellore, India, who advises SAGE, says in an article for journal Nature that these biologicals still have a major part to play. “These are not bad vaccines. They’re just vaccines that haven’t been optimized yet.”
The text published this month shows that CoronaVac is the world’s most widely used Covid-19 vaccine.
In mid-2021, the WHO approved these vaccines for emergency use, on the basis of limited clinical-trial data suggesting that CoronaVac was 51% and Sinopharm 79% effective at preventing symptomatic disease.
This was on a par with the 63% efficacy reported for the University of Oxford–AstraZeneca’s viral-vector vaccine at the time of its WHO listing, but lower than the 90% and higher efficacies of the mRNA vaccines developed by Pfizer–BioNTech and Moderna.
Both the Chinese vaccines are inactivated vaccines, which use the same SARS-CoV-2 virus. This type of vaccine seems to be less potent because it triggers an immune response against many viral proteins.
By contrast, mRNA and viral-vector vaccines target the response to the spike protein, which is what the virus uses to enter human cells.