Analysis of SARS-CoV-2 breakthrough infections with variants and vaccines

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has infected more than 262 million people and killed more than 5.2 million people since its appearance in December 2019. Despite the high efficacy of currently available vaccines, breakthrough SARS-CoV-2 infection real-world studies have reported in fully vaccinated individuals.

The highly infectious SARS-CoV-2 mutant (VOC) has been found to be the leading reason for post-immune breakthrough infections. Most SARS-CoV-2 mutants Spike proteinFew mutations in the receptor-binding domain (RBD) of peplomers lead to high infectivity and anti-immunity.

study: Investigation of SARS-CoV-2 breakthrough infections by subspecies and vaccine type.. Image Credits: WirestockCreators / Shutterstock.com

About research

In the preprint study published in medRxiv* On the server, researchers found the distribution of the SARS-CoV-2 genotype identified in 378 fully vaccinated individuals in the South Limburg region of the Netherlands from January to July 2021. Compared to the prevalence of the mutation identified by 2 regional surveillance.

In the current study, patients who received a complete SARS-CoV-2 vaccine were given 14 days or more after two doses of Pfizer-BioNTech, Modena, or Oxford-AstraZeneca vaccine, or 14 days after one dose of Johnson. It is defined as above. & Johnson vaccine, or coronavirus disease 2019 (COVID-19) -related symptoms that develop and are subsequently tested positive for COVID-19 by real-time polymerase chain reaction (RT-PCR) or antigen test.

Patients with COVID-19-related symptoms such as cold, loss of taste and smell, diarrhea, nausea, malaise, and headache were considered symptomatic. Cases with no COVID-19-related symptoms reported on positive testing and no symptoms during the 7-day follow-up period were classified as asymptomatic.

Hospitalized cases and cases with fatal consequences were classified as severe, and the remaining cases were considered mild to moderate. The current study hired trained personnel to collect a combination of nasopharyngeal / oropharyngeal swabs with virus transport medium. Virus sequencing and mapping data were statistically analyzed.

Investigation result

The results of the current study show that breakthrough cases continue to appear infrequently before the development of delta mutants, and the proportion of SARS-CoV-2 mutants that cause breakthrough infections is those mutants in the region. It was shown to be in good agreement with the distribution of.

However, as the delta variant became predominant in the region, the proportion of breakthrough cases to the total number of cases appeared to increase. It was difficult to determine if an increase in the relative rate of breakthrough infections was associated with an increase in delta mutants. During that period, the number of fully vaccinated individuals also increased.

The authors also found that the messenger ribonucleic acid (mRNA) -based vaccine (0.14%) had less breakthrough infections compared to the Johnson & Johnson / Janssen (0.46%) or Oxford-AstraZeneca vaccine (0.89%). I noticed. Of the administered vaccine. Significant differences in median age were also observed when fully vaccinated individuals with severe symptoms were compared to individuals with asymptomatic cases or mild to moderate symptoms.

No association has been established between the SARS-CoV-2 genotype or vaccine type and the symptoms of the disease. In addition, higher viral loads were found in symptomatic individuals compared to asymptomatic vaccinated individuals.

Delta variant-driven breakthrough infections were associated with increased viral load compared to those caused by alpha variants. These findings suggest that the emergence of delta variants reduces the efficiency of certain types of vaccines and makes older people more vulnerable to the severe illnesses of SARS-CoV-2 breakthrough infections.

Limitations and conclusions

This study has some limitations. The number of breakthrough infections reported is underestimated because asymptomatic or mild cases from local hospitals have not been reported to local public health services. Also, asymptomatic cases were only followed for a short period of time, which could underestimate symptomatic cases.

In conclusion, in this study, SARS-CoV-2 breakthrough infections were more common in people vaccinated with Oxford-AstraZeneca or Johnson & Johnson / Janssen compared to those vaccinated with mRNA-based vaccines. It turned out that it was observed. Breakthrough infections increased rapidly with the predominance of delta mutants, but serious illness was seen in the elderly.

Booster shots for specific vaccines and at-risk populations, as the Delta variant appears to reduce vaccine efficacy and increase viral load in both vaccinated and unvaccinated individuals. May help prevent future outbreaks of COVID-19.

“Breakthrough infections were found to be more frequently observed in people receiving Oxford-AstraZeneca or J & J / Janssen compared to recipients of mRNA-based vaccines.”

*Important Notices

medRxiv publishes unpeer-reviewed preliminary scientific reports and should not be considered definitive, guide clinical / health-related behaviors, or be treated as established information.