In Shanghai: Chinese vaccines show "high and durable" effectiveness against critical illness & death, "low" against infection

Preprint reports real-world vaccination effectiveness data from Omicron BA. 2 outbreak

In an English-language preprint available since Sep. 9, 2022, but somehow yet to find its way to media reports and public opinion, Chinese scientists have disclosed real-world data on the effectiveness of Chinese COVID vaccines from the Omicron outbreak in Shanghai which at the time dominated headlines across the world.

Their main findings are as follows:

• Inactivated vaccines, the most widely used in the Chinese mainland and namely the Sinovac and Sinopharm shots, were 16.3% effective against infection, 88.6% effective against severe/critical COVIID-19, and 91.7% against COVID-19 death.

• Ad5-vectored vaccines, less widely used in China, were 13.2% effective against infection and 77.9% effective against severe/critical COVIID-19.

• Booster vaccination with inactivated vaccines enhanced protection against severe COVID-19 (92.7%) and COVID-19 death (95.9%).

• Inactivated vaccine effectiveness against infection began to wane 12 weeks after the last dose but two- and three-dose sustained high protection levels (>80%) against severe/critical illness and death.

• Over 85% of the SARS-CoV-2 infections reported from Shanghai by China’s National Health Commission were asymptomatic.

• The most common age for infection was 40-59 years of age (37.3%); the most common age for severe/critical COVID-19 and COVID-19 death was 80 years and older (58.6% of severe/critical COVID-19 and 69.9% of COVID-19 deaths).

• At the beginning of the study period, 82.7% people received at least one dose of a COVID-19 vaccine, with the majority 18-59-years old. The prevalence of the adult-focused booster dose increased from 11.9% to 49.0%. Full and partial coverage among adults aged 80 years and above was low and stable at approximately 15%.

Background as provided in the preprint:

• Between 2 December 2021 and 13 May 2022, a total of 618,019 individuals tested RT-PCR-positive for SARS-CoV-2 infection in Shanghai. The study which produced the preprint studied 612,597 documented infections, among which 1,485 progressed to severe or critical illness and 568 died.

• Since March 12, a series of emergency epidemic prevention measures were implemented in Shanghai, including mass nucleic acid amplification testings, citywide lockdowns, home quarantine of residents, isolation of cases, centralized quarantine of close contacts, and closed-loop management. The rapid spread of Omicron led to temporary suspension of vaccination starting in March 2022.

The authors wrote in CONCLUSION

Our study showed high and durable two- and three-dose inactivated VE against severe/critical COVID-19 and death caused by Omicron infection across all age group, but with lower effectiveness against Omicron infection. Everyone eligible should be vaccinated; individuals eligible for booster doses should receive timely boosters; improving coverage among the elderly is especially important. The vaccines being used in China are highly effective where it matters most - preventing severe illness and death – and are most effective when boosted.

Read the preprint (meaning it hasn’t been peer-viewed by fellow scientists).

Photo by Denys Nevozhai on Unsplash

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I'm obviously not a scientist and having read a lot on COVID I’m sure scientists will tell you how flawed it is to make the following comparisons because the parameters are so different, BUT you and I most likely do not have MDs or relevant PhDs and it is simply human nature to make such them:

• As the preprint reports, Chinese inactivated vaccines (read: Sinovac and Sinopharm shots) against the Omicron BA. 2 variant were 88.6% effective against severe/critical COVIID-19 on two doses and 92.7% on three doses/booster shots.

• As a peer-reviewed and published paper in Nature Medicine reported, on 21 February 2022, based on a large, diverse study population included 26,683 SARS-CoV-2 test-positive cases, the vaccination effectiveness of mRNA-1273 (read: Moderna) against hospitalization in the Omicron (B.1.1.529) variant were 84.5% for two doses and 99.2% for three doses.

So if - a huge “if”, given the standards are obviously different - we clumsily equal Shanghai’s “severe/critical COVID” with the “hospitalization” in the U.S., you get

88.6% in Chinese Sinovac/Sinopharm vaccines vs 84.5% in Moderna, on two doses

92.7% in Chinese Sinovac/Sinopharm vaccines vs 99.2% in Moderna, on three doses

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Another perhaps more flawed but also all-too-human comparison is on the vaccination effectiveness against infection.

The Shanghai preprint reports that “inactivated vaccine was 16.3% effective against Omicron BA. 2 infection” with the caveat that “lower vaccination effectiveness” against Omicron infection in younger adults may be partly due to a higher force of infection in working-age adults or differences in willing to be vaccinated (although vaccination rates were very high in all ages under 60 years).”

The peer-reviewed and published paper in Nature Medicine reported the two-dose Moderna vaccines’ effectiveness against Omicron (B.1.1.529, which is different from BA. 2) infection was 44.0% at 14–90 days and declined quickly to 23.5% at 91–180 days, 13.8% at 181–270 days, and 5.9% at >270 days. The three-dose vaccination effectiveness against Omicron (B.1.1.529) infection was 71.6% at 14–60 days and 47.4% at >60 days.

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The comparisons need to be made partly because it has been well-established in the Western narrative that

1) Chinese vaccines are far less “effective” than mRNA vaccines, which China for whatever reasons has refused to use;

2) One major reason for Beijing’s lack of confidence in dropping the stringent COVID controls is that Chinese vaccines are far less effective and Beijing knows it, although it never admits it.

I think a fair assessment is when it comes to protection against hospitalization/severe COVID-19 and deaths, Chinese vaccines have about similarly high effectiveness as mRNA vaccines do; when it comes to preventing infection, Chinese vaccines indeed appear less effective on the numbers, but even if all Chinese get mRNA vaccinations, still around/about/approximately half cannot be protected from infection - far from being able to achieve anything nearing zero infection, *IF* that remains the Chinese policy goal.