Relative vaccine effectiveness against Delta and Omicron COVID-19 after homologous inactivated vaccine boosting: a retrospective cohort study

Abstract

ObjectiveTwo COVID-19 outbreaks occurred in Henan province in early 2022—one was a Delta variant outbreak and the other was an Omicron variant outbreak. COVID-19 vaccines used at the time of the outbreak were inactivated, 91.8%; protein subunit, 7.5%; and adenovirus5-vectored, 0.7% vaccines. The outbreaks provided an opportunity to evaluate variant-specific breakthrough infection rates and relative protective effectiveness of homologous inactivated COVID-19 vaccine booster doses against symptomatic infection and pneumonia.DesignRetrospective cohort studyMethodsWe evaluated relative vaccine effectiveness (rVE) with a retrospective cohort study of close contacts of infected individuals using a time-dependent Cox regression model. Demographic and epidemiologic data were obtained from the local Centers for Disease Control and Prevention; clinical and laboratory data were obtained from COVID-19-designated hospitals. Vaccination histories were obtained from the national COVID-19 vaccination dataset. All data were linked by national identification number.ResultsAmong 784 SARS-CoV-2 infections, 379 (48.3%) were caused by Delta and 405 (51.7%) were caused by Omicron, with breakthrough rates of 9.9% and 17.8%, respectively. Breakthrough rates among boosted individuals were 8.1% and 4.9%. Compared with subjects who received primary vaccination series ≥180 days before infection, Cox regression modelling showed that homologous inactivated booster vaccination was statistically significantly associated with protection from symptomatic infection caused by Omicron (rVE 59%; 95% CI 13% to 80%) and pneumonia caused by Delta (rVE 62%; 95% CI 34% to 77%) and Omicron (rVE 87%; 95% CI 3% to 98%).ConclusionsCOVID-19 vaccination in China provided good protection against symptomatic COVID-19 and COVID-19 pneumonia caused by Delta and Omicron variants. Protection declined 6 months after primary series vaccination but was restored by homologous inactivated booster doses given 6 months after the primary series.

Structure–Activity Relationship Studies of SARS-CoV-2 Main Protease Inhibitors Containing 4-Fluorobenzothiazole-2-carbonyl Moieties

“…38 Therefore, compounds ( 7) and (8), which have a 7-fluoro-or 4,7-difluoro-indole at the P3 site with 4-fluorobenzothiazole at the P1′ site and the same P2 structure as that of nirmatrelvir (1), were designed. The fluorinated derivatives (7) and (8) showed enhanced activities compared to compound 32 but were less active than compound 3. The hybrid compound (9) possessing the same P1′, P1, and P2 moieties as those of compound 3 and the same P3 moiety as that of nirmatrelvir (1) did not show improved activity compared to compound 3.…”

“…38 Therefore, we envisioned that hybrid molecules of compound 3 combined with nirmatrelvir (1) could result in novel, potent, and orally administered M pro inhibitors. We initially designed and synthesized compounds (7), (8), (9), and TKB245 (5) as such hybrid molecules. In the case of compounds (3) and ( 4), replacement of P1−P2 amide with a thioamide improved their PK profiles in mice, and so, because TKB245 (5) 42 showed the most potent anti-SARS-CoV-2 activity among the hybrid molecules, 42 a TKB245 (5) thioamide derivative, TKB248 (6), was designed and synthesized.…”

“…Since the emergence in 2019 of a relevant positive-sense single-stranded RNA virus, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the pandemic of the novel coronavirus disease 2019 (COVID-19) caused by this virus has expanded throughout the world and continues even in 2023. – To date, more than 30 kinds of vaccines that include those that target the recently spreading omicron strain have been developed and used clinically worldwide to suppress the infection of SARS-CoV-2 and aggravation of the symptoms. – However, the efficacy of these vaccines varies due to frequent mutations of their target sites in the spike protein on the virion surface. , Furthermore, there are many who, for various reasons, decline to take the vaccines . For these reasons, effective medicines for the treatment of COVID-19 are needed.…”

The relative prevalence of the Omicron variant within SARS-CoV-2 infected cohorts in different countries: A systematic review

“… 90 Additionally, the Omicron Variant demonstrated a breakthrough infection rate of 17.8% while the Delta variant had a rate of just 9.9% (Tang et al). 91 …”

Panorama of Breakthrough Infection Caused by SARS-CoV-2: A Review

“…Based on a multicenter study in 11 general hospitals in Israel, Cohen found that, as of 31 January 2022, 4802 (20%) of the 24,280 health care workers who received boosters and 368 (7%) of the 5331 health care workers who received the fourth dose of vaccine suffered a breakthrough infection during the peak of Omicron infection [33]. Moreover, based on data from Henan, China, in January 2022, Tang reported that the breakthrough infection rate was 17.8% in the Omicron chain [34]. Nowadays, the number of persons vaccinated with at least one dose per 100 population is approximately 89 in China, which is one of the countries with the highest vaccination rate in the world, but it is experiencing a surge in breakthrough infections caused by Omicron [1].…”