China’s flagship Covid vaccine may offer virtually no protection against Omicron
China’s Covid vaccine may offer virtually no protection against Omicron, scientists have warned.
Two doses of the CoronaVac shot were found to cause ‘undetectable’ antibody levels in Yale University lab studies.
A Pfizer booster increased antibody levels in those who were double vaccinated with the China-made injection, but only to levels comparable to people who received two Pfizer or Moderna injections, the team said.
The finding suggests that the billions of people who have received the shot have no protection against infection.
CoronaVac, manufactured by the Chinese pharmaceutical giant Sinovac, is authorized in 50 countries around the world.
Professor Akiko Iwasaki, an immunobiologist at Yale and senior author of the study, warned that “an additional booster shot — and possibly two” may be needed in these countries.
It will come as a warning sign to China, which has relied only on its homegrown jabs, including Sinopharm.
China – which reported just 0.09 cases per million people yesterday, compared to the UK’s 1,357 per million – has returned to draconian local lockdowns in the past month.
CoronaVac uses an inactivated version of the virus to boost the body’s immune response.
Vaccine skeptics in the West had promoted the Chinese shot as a better and safer alternative to new mRNA shots because they use traditional technology.
Yale University researchers who studied blood samples from 100 people who had been pricked with Sinovac twice did not produce an antibody response to Sinovac (red bar). Blood samples taken from the same group 28 days after a Pfizer booster shot (orange bar) showed that antibody levels had increased compared to those who received only two Sinovac shots. However, this response was the same as that seen in people who were double stung with Pfizer or Moderna (blue bar) alone, the researchers said. The test used to measure antibody levels (shown on the vertical axis) does not match the number of antibodies produced by each injection
Sinovac (pictured) uses an inactivated version of the virus to boost the body’s immune response. The vaccine — which can be stored at refrigerator temperature, making it easy to distribute to developing countries — has been approved in about 50 countries
China – which yesterday reported just 0.09 cases per million people – has returned to draconian local lockdowns (green line) in the past month. It follows a zero Covid plan. By comparison, the UK registered 1,357 cases per million people yesterday (purple line).
Chile – the most stimulated nation in the world, where 63 percent of the population has been stabbed three times – relies on CoronaVac after signing a deal with China for 1.8 million doses by 2020. Denmark and the UK and the next countries with the most boosters, with 59 and 54 percent of their populations rumen prickly, respectively
The Yale University study examined blood samples taken from more than 100 people who had received a double shot with CoronaVac.
It did not look at the vaccine’s effect as a booster, with third doses to be distributed in China from October.
But even giving a dose of Moderna or Pfizer to people who received two CoronaVac shots only matched their antibody levels with two injections of the mRNA shots.
Professor Iwasaki said: ‘An additional booster injection – and possibly two – is clearly needed in areas of the world where the Sinovac injection has been the main source of vaccination.
“Booster shots are clearly needed in this population because we know that even two doses of mRNA vaccines do not provide adequate protection against infection with Omicron.”
Despite not offering much protection against getting Covid, two shots from Pfizer still reduce the risk of serious illness.
Chile — the most stimulated country in the world, where 63 percent of the population has been stabbed three times — has relied on CoronaVac after signing a 2020 deal with China for 1.8 million doses.
But it is now using AstraZeneca and Pfizer for booster shots after a series of studies suggested the Chinese injection offered less protection.
Countries in Africa, the Middle East and Europe also use CoronaVac. According to the Oxford University platform Our World in Data, approximately 60 million doses have been distributed in Europe alone.
Two doses of AstraZeneca and Johnson & Johnson’s shots have been shown in studies to produce a low antibody response to Omicron, but field data often differ from study data because antibodies are only a limited measure of the complex immune response.
For example, Pfizer’s vaccine, which is considered the gold standard, was found to activate 40 times fewer antibodies against Omicron compared to older variants.
But the UK Health Security Agency claims it still offers up to 40 percent protection against Omicron, while a booster brings the figure to around 80 percent.
Yale researchers, who collaborated with scientists from the Dominican Republic’s Department of Health for the latest study.
HOW DOES SINOVAC WORK?
Sinovac uses an inactivated version of the virus to boost the body’s immune response.
The vaccine — which can be kept at refrigerator temperature, making it easy to distribute to developing countries — has been approved in about 50 countries.
It is given as two doses, two to four weeks apart.
Researchers at Brazil’s Butantan Biomedical Center found last January that Sinovac was 78.4 percent effective against “mild to severe” cases requiring treatment.
However, field data from Peru, which has used the jab, shows that two doses reduce the risk of infection by only 50.4 percent. However, their data also showed that the jab was still close to 94 percent effective at reducing the risk of death.
And Yale University researchers said the jab provides 85 percent protection against hospitalization with the virus and cuts the risk of dying from Covid by 80 percent.
Last April, the head of China’s Center for Disease Control and Prevention, Gao Fu, admitted the shots “do not have a very high degree of protection” against symptoms of the coronavirus.
They took blood samples from 101 people in the Dominican Republic who had received a double shot with Sinovac.
Participants also gave a second blood sample seven and 28 days after they received a Pfizer booster, which was injected at least four weeks after their second shot.
The scientists exposed these samples to Omicron, as well as the previously dominant Delta and the first version of the virus, which was seen in Wuhan.
The results, published in naturopathyshow that people who double-sticked with Sinovac did not produce neutralizing antibodies against the super mutant Omicron, which was first discovered by South Africa in November.
But 28 days after a Pfizer booster shot, their antibody protection against Omicron jumped compared to those who only got two Sinovac shots.
However, this response was the same as that seen in people who were double-pricked with Pfizer or Moderna alone, the researchers said.
Separate blood analysis revealed that those who had two Sinovac injections and a Pfizer booster produced 10.1 times fewer antibodies against Omicron compared to the original Covid strain and 6.3 times less against Omicron than Delta, the researchers said.
The researchers also found that people infected with Covid earlier in the pandemic had little immune protection against Omicron.
Scientists have warned that the immune response induced by two doses does not provide adequate protection against Omicron, a finding that prompted Britain’s winter booster campaign.
Omicron’s extensive mutations — most of which are on the spike protein the virus uses to infect the body’s cells — make the protection caused by previous infection or vaccination less effective.
This is because existing vaccines are designed to elicit an antibody response against known spike proteins.
The team cautioned that their findings are likely to complicate efforts to combat the milder but more transmissible strain of Omicron.
However, Professor Iwasaki noted that the vaccines and previous infections trigger other parts of the immune system on top of antibodies, such as T cells that can attack and kill infected cells and prevent serious disease.
“But we need antibodies to prevent infection and slow transmission of the virus,” she warned.