Abstract
Although laboratory data show that antibody responses to COVID-19 immunization give superior neutralization of certain circulating variations to spontaneous infection, few real-world epidemiological studies demonstrate the advantage of vaccination for previously infected individuals. This paper summarizes the outcomes of a case–control study conducted in Romania between March 2020 and October 2021 on patients previously infected with SARS-CoV-2. A case–control study was implemented after identification of 62 breakthrough cases. These cases were matched by age and gender to a 1:1 ratio with a control group of unvaccinated patients with SARS-CoV-2 reinfection status. There were no significant differences in the severity of cases and mortality between the study groups. However, unvaccinated patients had a shorter protection from natural immunity than patients with full vaccination status (58 days versus 89 days). The unvaccinated cases with SARS-CoV-2 reinfection were also statistically more likely to have a longer hospital admission duration (12.4 days versus 9.8 days), and required more non-invasive oxygen supplementation during their stay than breakthrough cases (37.1% versus 19.4%). Individuals with prior SARS-CoV-2 infection who were not vaccinated are not at a higher risk of severe COVID-19 infection or mortality compared to those who were completely vaccinated with the mRNA vaccine Comirnaty® Pfizer/BioNTech BNT162b2 and acquired a breakthrough infection within 2–3 months of the previous infection with a Beta or Delta SARS-CoV-2 variant. Although our findings are consistent with natural immunity offering similar short-term protection to a second dose of mRNA vaccine, all eligible individuals should be provided with immunization to lower their risk of infection, even if they have already been infected with SARS-CoV-2.
Highlights
Due to a lack of efficient treatments, numerous attempts have been undertaken to avoid infection and sickness since the discovery of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as the causative agent of coronavirus disease 19 (COVID-19) in late 2019
Between February 2020 and October 2021, approximately 1.7 million Romanians were infected with SARS-CoV-2, while more than 4 million people received a second vaccine dose since the start of the vaccination campaign in December 2020, until October 2021, with the Comirnaty® Pfizer/BioNTech BNT162b2 vaccine [20]
Infection transmission in the breakthrough cases was unknown in 61% of admissions, compared to 32% in reinfection cases, where the major route of transmission was within the household (42%)
Summary
Due to a lack of efficient treatments, numerous attempts have been undertaken to avoid infection and sickness since the discovery of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as the causative agent of coronavirus disease 19 (COVID-19) in late 2019. After the World Health Organization declared a global pandemic in early 2020 [1], a race to develop a functional vaccine was carried out in the majority of countries possessing advanced research capabilities. Since its launch in late 2020, the messenger RNA (mRNA) vaccine (Comirnaty® Pfizer/BioNTech BNT162b2) has proved to be very successful in preventing clinically significant COVID-19 [3]. Several approved vaccines showed great effectiveness in protecting against SARS-CoV-2 infection, ranging from 70% to 95% for the Beta variant. After promising trial results, vaccination recipients have had breakthrough infections, a situation that has been documented in various nations and health care organizations [7]. There has been no published investigation of the correlation between protection against breakthrough infection and the type of vaccine
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
