Real-world research in Singapore reveals the role of mRNA and inactivated vaccines in preventing new coronavirus infection and risk of severe disease

A new Singapore study compares the efficacy of a Covid-19 vaccine for Covid-19 infection and severe prevention, published in Clin Infect Dis on April 12, 2022
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 The study aimed to compare the four available vaccines in Singapore and to investigate the results of other studies showing that mRNA vaccines have higher efficacy than non-mRNA vaccines
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The four vaccines are Pfizer-BioNTech/Comirnaty and Moderna, which are mRNA vaccines, and Sinovac-CoronaVacvaccine and Sinovac, which are non-mRNA vaccines that use inactivated viruses to trigger an immune response
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The Pfizer vaccine was used as a reference as it is most commonly used in Singapore
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The study looked at the incidence of Covid-19 infection and severe illness between October 1 and November 21, 2021, using an official database maintained by the Ministry of Health (MOH) in Singapore
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The investigators restricted the cohort to two weeks after completion of two doses of vaccine to generate an adequate immune response, and received a second dose of vaccine to control for weakened immunity within 120 days of our analysis
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Separately, "serious illness" was defined as requiring supplemental oxygen in a hospital, admission to an intensive care unit, or death
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Within 14 to 120 days of receiving two doses of the vaccine, 2,709,899 people were enrolled in the study cohort, of whom 2,001,181 (74%) received Pfizer BioNTech/Comirnaty, 628,012 (23%) received Moderna, and 60,407 (2%) received Sinovac CoronaVac and 20,299 (1%) for Sinopharm
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During the study period, 107,220 people were confirmed to be infected with COVID-19 by PCR, of whom 644 developed severe disease
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Individuals vaccinated with Sinovac-CoronaVac were more likely to be infected after adjusting for age, sex, race, residential status, socioeconomic status, time since second vaccination, and daily infection rate (adjusted IRR 2.
37 ; 95% CI 2.
29 – 2.
46) and were more likely to develop severe disease (adjusted IRR 4.
59; 95% CI 3.
25 – 6.
48); individuals vaccinated with Sinopharm also had a higher risk of infection compared with Sinopharm (adjusted IRR 4.
59; 95% CI 3.
25 – 6.
48) IRR 1.
62; 95% CI 1.
43 – 1.
85), while Moderna-vaccinated individuals had a lower risk of severe disease (adjusted IRR 0.
42; 95% CI 0.
25 – 0.
70) compared with those receiving Pfizer-BioNTech/Comirnaty (Table 1).
1)
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In other words, taking the Pfizer mRNA vaccine as a reference, people treated with Sinovac-CoronaVac: 2.
37 times more likely to be infected than those treated with Pfizer; those who received Sinovac-CoronaVac were infected Those who received Pfizer were 1.
62 times more likely; and those who received Moderna were 0.
84 times more likely to be infected than those who received Pfizer
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In the prevention of severe disease caused by Covid-19 infection, people treated with Sinovac-CoronaVac were 4.
59 times more likely to develop severe disease than those treated with Pfizer; those treated with Sinovac, People who received Pfizer were 1.
62 times more likely to develop severe disease; people who received Moderna were 0.
42 times more likely to develop severe disease than those who received Pfizer
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In general, the comparison of the effects of each vaccine is Modena>Pfizer>Sinopharm>Kexing
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The investigators concluded that less protection against COVID-19 infection was observed in individuals vaccinated with 2 doses of the inactivated whole virus vaccine compared with individuals vaccinated with the mRNA vaccine
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Nonetheless, both mRNA vaccines and inactivated whole-virus vaccines provide adequate protection against severe COVID-19 disease, and vaccination remains a key strategy for responding to the pandemic
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Studies such as UK COV-BOOST have shown that a third dose provides additional protection against COVID-19, and future studies should continue to monitor the effectiveness of these vaccines and assess how further booster doses enhance them
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The study concluded that "both mRNA vaccines and inactivated whole virus vaccines provided adequate protection against severe Covid-19 disease" and affirmed the importance of vaccination as a "key strategy" in the Covid-19 pandemic
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"Our goal was to compare mRNA and inactivated whole virus vaccines in the same population, as these findings will help guide policy recommendations to prevent infection and reduce pressure on healthcare systems, " the study's authors said in their introduction
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However, Mays Medicine also reminded that although this study is very rigorous and has a large sample size, there are two important issues that need to be paid attention to: First, the study was conducted from October 1 to November 21, 2021.
During this period, Delta infection is still the main infection, not Omicron, and it is necessary to conduct a comprehensive evaluation of Omicron infection in the future
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At the same time, the latest Chilean study on the protective effect of Sinovac vaccines on children during Omicron, see: Chile research report Sinovac inactivated new coronavirus vaccine in real-world effects of children infected with Omicron-MedSci.
cn, via Only by making comprehensive judgments can we have a more comprehensive understanding of the role of vaccines
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Second, this study mainly evaluated the protective effect of two vaccine injections, and the effects of three injections were not compared
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Combined with the latest results in Hong Kong, the protective effect of three inactivated vaccines on severe illness and death in the elderly is similar to that of the mRNA vaccine (Pfizer).
For inactivated vaccines, the effect of three injections is far better than that of two injections; For mRNA vaccines, the effect of three injections is only limited compared to two injections
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Therefore, there is also a huge difference between the effects of two needles and three needles, and more data will be needed for evaluation in the future
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Reference [1] Premikha M, Chiew CJ, Wei WE, Leo YS, Ong B, Lye DC, Lee VJ, Tan KB.
Comparative Effectiveness of mRNA and Inactivated Whole Virus Vaccines against COVID-19 Infection and Severe Disease in Singapore.
Clin Infect Dis.
2022 Apr 12:ciac288.
doi: 10.
1093/cid/ciac288 Source | Edited by Mays official website |