Effectiveness of Covid-19 vaccines against SARS-CoV-2 Omicron variant (B.1.1.529): A systematic review with meta-analysis and meta-regression

Abstract

Background: There is a need for evaluation regarding vaccine effectiveness (VE) and the urgency of booster vaccination against Covid-19 B.1.1.529 (Omicron) variant. Methods: Systematic search was conducted on April 6th, 2022, on databases (PubMed, ScienceDirect, CENTRAL, Web of Science, Scopus). VE difference (VED) estimates were assessed using random-effects model and DerSimonian-Laird tau estimators. Two models result, i.e., within 3 months and within 3 months or more, are compared. VE versus time meta-regression analysis was evaluated using mixed-effects model with Restricted-Maximum Likelihood tau estimators and Hartung-Knapp adjustments. Results: Ad26.COV2.S, BNT162b2, ChAdOx1 nCov-19, and mRNA-1273 vaccines were included in the analyses. Compared to full dose, booster dose of overall vaccines provided better protection against any (VED=22% (95%CI 15%-29%), p<0.001), severe (VED=20% (95%CI 8%-32%), p=0.001) and symptomatic (VED=22% (95%CI 11%-34%), p<0.001) Omicron infections within 3 months, as well as within 3 months or more (VED=30% (95%CI 24%-37%), p<0.001 for any, VED=18% (95%CI 13%-23%), p<0.001 for severe and VED=37% (95%CI 29%-46%), p<0.001 for symptomatic infections). The meta-regression analysis of overall vaccines revealed that the full dose VE against any and symptomatic Omicron infections were significantly reduced each month by 3.0% (95%CI 0.9%-4.8%, p=0.004) and 5.2% (95%CI 3.3%-7.1%, p=0.006), respectively; whereas booster dose effectiveness against severe and symptomatic Omicron infections were decreased by 3.7% (95%CI 5.1%-12.6%, p=0.030) and 3.9% (95%CI 1.2%-6.5%, p=0.006), respectively. Conclusion: Compared to full dose only, a booster dose addition provides better protection against B.1.1.529 infection. Although the VE estimates of Ad26.COV2.S, BNT162b2, ChAdOx1 nCov-19, and mRNA-1273 vaccines against B.1.1.529 infection after both full and booster doses are generally moderate, and the booster dose provides excellent protection against severe infection, it is important to note that the VE estimates decline over time, suggesting the need for a regular Covid-19 booster injection after certain period of time to maintain VE.

The Potential Clinical Impact of Implementing Different COVID-19 Boosters in Fall 2022 in the United States

“…14 Data for boosters were obtained from a test-negative case-control study conducted in England, with assumptions applied for missing data. 15 For the Omicron BA.1 period, initial VE for primary series and booster and waning for the primary series were obtained from a meta-analysis by Pratama et al, 2022; 16 data collected in England 17 were used where meta-analytic data were unavailable. The waning rates for the booster were assumed to be the same as the waning rates for the primary series.…”

Impact of Differential Vaccine Effectiveness on COVID-19 Hospitalization Cases: Projections for 10 Developed Countries where Booster Vaccines were Recommended

“…Primary series VE for all vaccines against infection and monthly waning for mRNA-1273 and BNT162b2 were obtained from a meta-analysis conducted by Pratama et al, 2022. 15 Pratama identified studies available by April 6, 2022, including 12 from the US, 4 from Europe, 2 from South Africa, 2 from Qatar and 1 from Canada. Monthly waning for Ad26.COV2.S and ChAdOX1-S were calculated from a large study by Adams et al, 2022 in the US, 16 and the UK Health Security Agency (HSA) COVID-19 report, respectively.…”

“…Booster VE against hospitalization for BNT162b2 and Ad26.COV2.S were obtained from Pratama et al, 2022. 15 Similar to booster VE against infection, the HR from Hulme et al, 2022 4 for hospitalizations was applied the BNT162b2 booster hospitalization VE to obtain the VE of mRNA-1273. Data for ChAdOx1-S were unavailable from the Pratama meta-analysis.…”

“…Primary series VE for all vaccines against infection and monthly waning for mRNA-1273 and BNT162b2 were obtained from a meta-analysis conducted by Pratama et al, 2022. 15 Pratama identified studies available by April 6, 2022, including 12 from the US, 4…”

“…BNT162b2 was applied to the VE of BNT162b2 to obtain the VE of mRNA-1273. Given the small proportion of doses of Ad26.COV2.S delivered globally as a booster, data were unavailable, and were approximated by calculating the ratio between Ad26.COV2.S primary series infection to hospitalization VEs and applying it to Ad26.COV2.S booster hospitalization VE.Booster VE against hospitalization for BNT162b2 and Ad26.COV2.S were obtained from Pratama et al, 2022 15. Similar to booster VE against infection, the HR from Hulme et al, 20224 for hospitalizations was applied the BNT162b2 booster hospitalization VE to obtain the VE of mRNA-1273.…”