Venkata R Emani, Vivek K Pallipuram, Kartik K Goswami, Kailash R Maddula, Raghunath Reddy, Abirath S Nakka, Sravya Panga, Nikhila K Reddy, Nidhi K Reddy, Dheeraj Nandanoor, Sanjeev Goswami
Background: There were increased SARS-CoV2 hospitalizations and deaths noted during Omicron (B.1.1.529) variant surge in the UK despite decreased cases, and the reasons are unclear.
Methods: In this retrospective observational study, we analyzed reported SARS-CoV2 cases, hospitalizations, deaths, and variables that affect the outcomes (including ethnicity, deprivation score, vaccination disparities, and pre-existing conditions during the COVID-19 pandemic in the UK. The vaccine effectiveness among those ≥ 18 years of age was also analyzed (August 16, 2021-March 27, 2022).
Results: During the latter part of the Omicron variant surge (February 28-May 1, 2022 a significantly increased proportion of cases (23.7% vs 40.31.70 [1.70-1.71]; p<0.001) and hospitalizations (39.3% vs 50.3%; RR 1.28 [1.27- 1.30]; p<0.001) among ≥ 50 years of age, and deaths (67.89% vs 80.07%; RR 1.18 [1.16-1.20]; p<0.001) among ≥ 75 years of age was observed compared to the earlier period (December 6, 2021-February 27, 2022). There was a significant decline in case fatality rate (all ages [0.21% vs 0.39%; RR 0.54 (0.52-0.55); p<0.001], ≥ 18 years of age [0.25% vs 0.58%; RR 0.44 (0.43-0.45); p<0.001], and ≥ 50 years of age [0.72% vs 1.57%; RR 0.46 (0.45-0.47); p<0.001]) and the risk of hospitalizations (all ages [0.62% vs 0.99%; RR 0.63 (0.62-0.64); p<0.001], ≥ 18 years of age [0.67% vs 1.38%; RR 0.484 (0.476-0.492); p<0.001], and ≥ 50 years of age [1.45% vs 2.81%; RR 0.52 (0.51-0.53); p<0.001] during the Omicron variant surge (December 27, 2021-March 20, 2022) compared to the Delta variant surge (August 16-December 5, 2021). Both the unvaccinated (0.41% vs 0.77%; RR 0.54 (0.51-0.57); p<0.001) and vaccinated (0.25% vs 0.59%; RR 0.43 (0.42-0.44); p<0.001) populations of ≥ 18 years of age showed a significant decline in the case fatality rate during the Omicron variant surge versus the Delta variant surge. In summary, a significant decline in the risk of hospitalizations was observed among both the unvaccinated (1.27% vs 2.92%; RR 0.44 (0.42-0.45); p<0.001) and vaccinated (0.65% vs 1.19%; RR 0.54 (0.53-0.55); p<0.001) populations of ≥ 18 years of age during the same period. We observed negative vaccine effectiveness for the third dose since December 20, 2021, with a significantly increased proportion of SARS-CoV2 cases hospitalizations, and deaths among the vaccinated; and a decreased proportion of cases, hospitalizations, and deaths among the unvaccinated. The preexisting conditions were present in 95.6% of all COVID-19 deaths. We also observed various ethnicity, deprivation score, and vaccination rate disparities that can adversely affect hospitalizations and deaths among the compared groups based on the vaccination status.
Conclusion: There is no discernable optimal vaccine effectiveness among ≥ 18 years of age and vaccinated third dose population since the beginning (December 20, 2021) of the Omicron variant surge. Other data including preexisting conditions, ethnicity, deprivation score, and vaccination rate disparities need to be adjusted by developing validated models for evaluating vaccine effectiveness against hospitalizations and deaths. Both the vaccinated and unvaccinated populations showed favorable outcomes during the Omicron variant surge. The increased proportion of cases among the vaccinated population with suboptimal vaccine effectiveness was associated with a significantly increased proportion of hospitalizations and deaths during the Omicron variant surge. This underscores the need to prevent infections, especially in the elderly vaccinated population irrespective of vaccination status by employing uniform screening protocols and protective measures.