RESUMO
Background: After primary vaccination schemes with rAd26-rAd5 (Sputnik V), ChAdOx1 nCoV-19, BBIBP-CorV or heterologous combinations, the effectiveness of homologous or heterologous boosters (Sputnik V, ChAdOx, Pfizer-BioNTech, Moderna) against SARS-CoV-2 infections, hospitalisations and deaths has been scarcely studied. Methods: Test-negative, case-control study, conducted in Argentina during omicron BA.1 predominance, in adults ≥50 years old tested for SARS-CoV-2 who had received two or three doses of COVID-19 vaccines. Outcomes were COVID-associated infections, hospitalisations and deaths after administering mRNA and vectored boosters, < or ≥60 days from the last dose. Findings: Of 422,124 individuals tested for SARS-CoV-2, 221,993 (52.5%) tested positive; 190,884 (45.2%) and 231,260 (54.8%) had received 2-dose and 3-dose vaccination schemes, respectively. The 3-dose scheme reduced infections, hospitalisations and death (OR 0.81 [0.80-0.83]; 0.28 [0.25-0.32] and 0.25 [0.22-0.28] respectively), but protection dropped after 60 days to 1.04 [1.01-1.06]; 0.52 [0.44-0.61] and 0.38 [0.33-0.45]). Compared with 2-dose-schemes, homologous boosters after primary schemes with vectored-vaccines provided lower protection against infections < and ≥60 days (0.94 [0.92-0.97] and 1.05 [1.01-1.09], respectively) but protected against hospitalisations (0.30 [0.26-0.35]) and deaths (0.29 [0.25-0.33]), decreasing after 60 days (0.59 [0.47-0.74] and 0.51 [0.41-0.64], respectively). Heterologous boosters protected against infections (0.70 [0.68-0.71]) but decreased after 60 days (1.01 [0.98-1.04]) and against hospitalisations and deaths (0.26 [0.22-0.31] and 0.22 [0.18-0.25], respectively), which also decreased after 60 days (0.43 [0.35-0.53] and 0.33 [0.26-0.41], respectively). Heterologous boosters protected against infections when applied <60 days (0.70 [0.68-0.71], p < 0.001), against hospitalisations when applied ≥60 days (0.43 [0.35-0.53], p < 0.01), and against deaths < and ≥60 days (0.22 [0.18-0.25], p < 0.01 and 0.33 [0.26-0.41], p < 0.001). Interpretation: During omicron predominance, heterologous boosters such as viral vectored and mRNA vaccines, following Sputnik V, ChAdOx1, Sinopharm or heterologous primary schemes might provide better protection against death; this effect might last longer in individuals aged ≥50 than homologous boosters. Funding: None.
RESUMO
Objetivo: Evaluar la efectividad de esquemas primarios de Sputnik V, Astra-Zeneca, Sinopharm o combinaciones heterólogas seguidos de refuerzos a vector viral (Sputnik V, Astra-Zeneca) o ARNm (Pfizer-BioNTech, Moderna) frente a infecciones, hospitalizaciones y muertes por SARS-CoV-2. Material y métodos: Estudio de casos y controles con test negativo realizado en la provincia de Buenos Aires, durante el predominio de ómicron BA.1, que incluyó individuos ≥ 50 años con test positivo para SARS-CoV-2 que habían recibido 2 o 3 dosis de vacunas. Se registraron infecciones, hospitalizaciones y muertes después de administrar refuerzos con Sputnik V, Astra-Zeneca o ARNm. Resultados: De 422 124 personas analizadas para SARS-Cov-2, 221 993 (52.5%) presentaron test positivos; 190 884 (45.2%) y 231.260 (54.8%) recibieron esquemas de vacunación de 2 y 3 dosis, respectivamente. Los esquemas primarios con Astra-Zeneca, Sputnik V o vector viral, combinados con un refuerzo a vector viral, mostraron protección contra infecciones (OR: 0.94 [0.92 a 0.97]), hospitalizaciones (OR: 0.30 [0.26 a 0.35]) y muertes (OR: 0.29 [0.25 a 0.33]. Los esquemas primarios con Astra-Zeneca y Sputnik V más refuerzo de ARNm, o con Sinopharm más refuerzo de ARNm o vector viral otorgaron protección adicional contra infecciones (OR: 0.70 [0.68 a 0.71]). Hubo un efecto protector frente a hospitalizaciones y muertes (OR: 0.26 [0.22 a 0.31] y 0.22 [0.18 a 0.25]) en todos los casos. Conclusiones: Durante el predominio de ómicron, los refuerzos heterólogos con vacunas a vector viral y de ARNm, posteriores a los esquemas primarios de Sputnik V, Astra-Zeneca, Sinopharm o heterólogos, podrían proporcionar mejor protección y mayor duración del efecto contra la muerte en personas mayores de 50 años, en comparación con refuerzos homólogos
Objective: To evaluate the effectiveness of primary vaccination regimens involving Sputnik V, Astra-Zeneca, Sinopharm, or heterologous combinations followed by viral vector boosters (Sputnik V, As-traZeneca) or mRNA boosters (Pfizer-BioNTech, Moderna) against infections, hospitalizations and deaths caused by SARS-CoV-2. Material and methods: Case-control studies with negative tests conducted in the Buenos Aires province during the Omicron BA.1 predominance. The study included patients ≥ 50 years of age, who tested positive for SARS-CoV-2 and had received two or three doses of vaccines. Infections, hospitalizations, and deaths were registered following the administration of Sputnik V, AstraZeneca, or mRNA boosters. Findings: Out of 422 124 people tested for SARS-Cov-2, 221 993 (52.5%) had positive test results; 190,884 (45.2%) and 231 260 (54.8%) received two-dose and three-dose vaccination schemes, respectively. Primary regimens with AstraZeneca, Sputnik V, or viral vector, combined with a viral vector booster demonstrated protection against infections (OR 0.94 [0.92 to 0.97]), hospitalizations (OR 0.30 [0.26 to 0.35]) and deaths (OR 0.29 [0.25 to 0.33]. Primary regimens with AstraZeneca and Sputnik V combined with mRNA boosters, as well as pri-mary schemes with Sinopharm combined with mRNA or viral vectored boosters showed additional protection against infections (OR 0.70 [0.68 to 0.71]). There was a protective effect against hospi-talizations and deaths (OR 0.26 [0.22-0.31] and 0.22 [0.18 -0.25]) in all cases. Conclusions: During Omicron predominance, heterologous boosters with viral-vector and mRNA vaccines, administered after Sputnik V, AstraZeneca, Sinopharm, or heterologous primary regimens, could provide enhanced protection and prolonged effectiveness against mortality in individuals aged ≥ 50, compared to ho-mologous boosters
