Nationwide Effectiveness of First and Second SARS-CoV2 Booster Vaccines During the Delta and Omicron Pandemic Waves in Hungary (HUN-VE 2 Study)

Abstract

BackgroundIn Hungary, the pandemic waves in late 2021 and early 2022 were dominated by the Delta and Omicron SARS-CoV-2 variants, respectively. Booster vaccines were offered with one or two doses for the vulnerable population during these periods.Methods and FindingsThe nationwide HUN-VE 2 study examined the effectiveness of primary immunization, single booster, and double booster vaccination in the prevention of Covid-19 related mortality during the Delta and Omicron waves, compared to an unvaccinated control population without prior SARS-CoV-2 infection during the same study periods. The risk of Covid-19 related death was 55% lower during the Omicron vs. Delta wave in the whole study population (n=9,569,648 and n=9,581,927, respectively; rate ratio [RR]: 0.45, 95% confidence interval [CI]: 0.44–0.48). During the Delta wave, the risk of Covid-19 related death was 74% lower in the primary immunized population (RR: 0.26; 95% CI: 0.25–0.28) and 96% lower in the booster immunized population (RR: 0.04; 95% CI: 0.04–0.05), vs. the unvaccinated control group. During the Omicron wave, the risk of Covid-19 related death was 40% lower in the primary immunized population (RR: 0.60; 95% CI: 0.55–0.65) and 82% lower in the booster immunized population (RR: 0.18; 95% CI: 0.16–0.2) vs. the unvaccinated control group. The double booster immunized population had a 93% lower risk of Covid-19 related death compared to those with only one booster dose (RR: 0.07; 95% CI. 0.01–0.46). The benefit of the second booster was slightly more pronounced in older age groups.ConclusionsThe HUN-VE 2 study demonstrated the significantly lower risk of Covid-19 related mortality associated with the Omicron vs. Delta variant and confirmed the benefit of single and double booster vaccination against Covid-19 related death. Furthermore, the results showed the additional benefit of a second booster dose in terms of SARS-CoV-2 infection and Covid-19 related mortality.

Understanding COVID-19 Vaccine Effectiveness against Death Using a Novel Measure: COVID Excess Mortality Percentage

“…A study of Greece through November 2021 reported that RMR rose to around 20% at 6 months after second dose, but studies only three broad age groups [ 4 ]. A study of Hungary reported two-dose RMR versus the unvaccinated that rose steadily with age [ 9 ]. A study of Norway over July–November 2021 reported two-dose RMR against death, averaged over both mRNA vaccines, as being 6.6% after 10–17 weeks, increasing to 31.4% for 33+ weeks [ 16 ].…”

“…However, U.S. public health messaging on boosters remained muddled, with the value of boosters “lost in the sea of changing recommendations and guidance.” [ 30 ]. Even today, U.S. booster percentages lag behind many other countries [ 9 , 31 ], and public knowledge of booster recommendations is limited [ 32 ]. Our study provides strong evidence on booster value for ages 60+, which account for the vast majority of COVID-19 deaths, and nearly all vaccinee deaths.…”

“…Most studies on vaccine effectiveness against mortality (VE) have had limited controls for individual characteristics, often only age and gender [ 3 , 4 , 5 , 6 , 7 , 8 , 9 ], or study short time periods [ 5 , 10 , 11 , 12 ]. U.S.-based studies typically lacked population-level data [ 7 , 13 , 14 , 15 ], and studies with population-level data often have had limited information about health status [ 3 , 4 , 8 , 9 , 16 ]. Some studies used a test-negative design [ 10 , 14 , 15 ], which is prone to selection bias [ 17 ].…”

Fatigue, sleepiness and sleep quality are SARS-CoV-2 variant independent in patients with long COVID symptoms

“…Our study is based on the retrospective review of 412 cases who were referred to the post-COVID care of the Semmelweis University, Department of Pulmonology between February 2021 and June 2022. A total of 287 cases met the following inclusion criteria: (1) acute COVID-19 during either the 3rd (between February 2021 and July 2021; VOC: B.1.1.7, Alpha; N = 135), 4th (between August 2021 and December 2021; VOC: B.1.617.2, Delta; N = 89) or 5th (between January 2022 and June 2022; VOC: B.1.1.529, Omicron; N = 63) major epidemic waves which affected Hungary (Voko et al 2022 ; Kiss et al 2022 ), (2) diagnosis confirmed by SARS-CoV-2 polymerase chain reaction (PCR) or a rapid immunoassay test, (3) presentation > 4 weeks after the acute course of COVID-19, and (4) complete medical records on anthropometric and self-reported questionnaire data (Fig. 1 ).…”

“…In this study, we investigated fatigue, sleepiness and sleep quality in long COVID patients who were infected with SARS-CoV-2 during either the 3rd, 4th or 5th major epidemic waves of COVID-19 in Hungary. Since these waves are known to be dominated by Alpha, Delta and Omicron VOCs, respectively (Kiss et al 2022 ; Voko et al 2022 ), we aimed to understand the unique characteristics of these novel viral variants.…”