Recently, a data chart about the infection efficiency of Sinovac has been circulated on the Internet. The figure shows that according to the latest data on the fifth round of the epidemic in Hong Kong, Sinovac’s effectiveness in preventing Omicron is low. Even after the third dose, the effectiveness in preventing infection is only 36% 14 days after vaccination, and only 8% remains after 6 months.
So, is this really the case?
This is not a real statistical data
Through tracing the source, we found that this picture was first seen in February this year, a media report on a University of Hong Kong epidemic development simulation model. The data content is the result of model projections, not the real statistics of Hong Kong society.
html On December 10, the School of Public Health of the University of Hong Kong released a simulation model for the development of the fifth wave of epidemics, which used data from different medical studies to calculate the effectiveness of each vaccine combination at different periods. The study estimated that the effectiveness of preventing Omicron variant virus infection on the 14th day after the third dose of the Sinovac vaccine was 36%, which dropped to 8% six months later.
So, what is the real situation? According to the epidemic data released by Hong Kong on December 23, in the fifth round of the epidemic (from December 31, 2021 to December 21, 2022), a total of 2.32 million people were infected in Hong Kong, more than 7.04 million people have received at least one dose of vaccine, and 627,000 people have received the fourth dose of vaccine. According to a rough calculation, there is no big difference in the proportion of infections when is vaccinated with the inactivated vaccine and the mRNA vaccine.
Taking the proportion of infections after the fourth dose as an example, the average infection proportion of those vaccinated with inactivated vaccine is 11.97%, while the proportion of infections with mRNA vaccine is 8.99%, the difference between the two is 2.97%. This difference decreases with age. Among those over 80 years old, the difference in infection proportion between the two is only 0.93%.
And, as the number of vaccine doses administered increases, the effectiveness in preventing infection increases.
is slightly less effective at preventing infection and inactivation than the mRNA vaccine
. Although there is no big difference between the two in actual infection rates, from the perspective of preventing infection, the effectiveness of the inactivated vaccine in preventing infection is indeed lower than that of the mRNA vaccine.
The study found that the effectiveness of the inactivated vaccine (31%) was slightly lower than that of the mRNA vaccine (47%) 7 days after the same three doses of vaccine.
The effectiveness of both decreases over time, and both are short-term effective prevention new crown . However, in comparison, the effectiveness period of inactivated vaccines is shorter. The
mRNA vaccine antibody retains effective concentrations in the blood for a longer period of time, and its effectiveness decreases by half after 104 days. The half-degeneration cycle of inactivated vaccines is about 40 days.
The effectiveness may be related to the technology used in the vaccine. The
mRNA vaccine contains the messenger ribonucleic acid (mRNA) of the virus . Its working principle is to send instructions to the host cells to copy the spike protein, so that the immune mechanism can produce antibodies in time to respond to the virus. Inactivated vaccines, on the other hand, inject complete, killed copies of the virus so that it cannot replicate without causing disease.
use different technologies, so their effectiveness is also different.
The inactivated vaccine is equally effective in preventing severe illness and death.
Although it is insufficient in preventing infection, the inactivated vaccine is as effective as or even better than the mRNA vaccine in preventing severe illness and death.
According to a paper published by National University of Singapore School of Medicine in November this year, although the antibody response induced by inactivated vaccines is not as good as that of mRNA vaccines, inactivated vaccines can trigger a broad immune response targeting different proteins on the virus, more effective against severe infections
In other words, the case fatality rate of people who have not been vaccinated is 71.8 times higher than that of people who have received three injections of the Sinovac vaccine.
Although my country is currently adjusting to "Category B" for new coronavirus infections, "protecting health and preventing severe disease" is still the focus of epidemic prevention, and continuing to promote vaccination, especially vaccination of the elderly is still very necessary.
