Study suggests aerosolized antibody delivery may contribute to host protection against SARS-CoV-2

Since the onset of the coronavirus disease 2019 (COVID-19) pandemic, caused by the rapid outbreak of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), scientists have worked at unprecedented speed to understand the different aspects of the virus. They developed several effective vaccines that significantly reduced severe infection rates and deaths from SARS-CoV-2 infection.

Study: Evidence for aerosol transfer of specific humoral immunity to SARS-CoV2. Image Credit: ktsdesign/Shutterstock

Background

Previous studies have indicated that high levels of antibodies (IgG and IgA) are present in the nasal cavity and saliva of vaccinees. These antibodies have been detected in humans and primates inoculated with mRNA- or protein-based vaccines. Several studies have revealed the respiratory transmission of a viral infection. These reports have highlighted that constituents of the oral/nasal cavity can be transferred by aerosols and/or respiratory droplets. In addition, scientists also felt that antibodies present in the oral/nasal environment may be aerosolized to some degree. A very limited amount of evidence shows the transfer of constituents (e.g. antibodies) present in the nasal/oral cavities, other than infectious particles, between two individuals.

A new study

A new study published on the medRxiv* The preprint server closed the previously mentioned research gap and investigated the possibility of transfer of aerosols containing SARS-CoV-2 specific antibodies between vaccinated and non-immune hosts.

The authors of this study indicated that certain rules were put in place to restrict the transmission of SARS-CoV-2 infection, such as making mask wearing mandatory in social and work settings, which presented an opportunity unique to determine the possibility of aerosol antibodies. expiration of vaccinated persons.

In this study, scientists applied a previously used method related to the isolation of antibodies from rehydrated dried blood (DBS) spots. They used this method to detect specific anti-SARS-CoV-2 antibodies eluted from surgical masks worn by vaccinated lab members, which were donated at the end of a working day.

Main conclusions

The results of this study are consistent with previous reports that found the presence of IgG and IgA in the saliva of vaccinated individuals. Scientists successfully identified IgG and IgA after eluting antibodies from face masks. Because of these observations, they hypothesized that aerosolized droplet/antibody transfer could occur between individuals, similar to the transfer of aerosolized viral particles from one individual to another.

To test the hypothesis, the researchers performed a multiplex microsphere immunoassay (MMIA) based on flow cytometry to detect SARS-CoV-2 specific antibodies in serum samples obtained from adult first responders in Arapahoe County, Colorado. Additionally, nasal swabs were collected from parents and their children at the Colorado Tricountry Vaccination Center in Aurora who were attending vaccination appointments, not limited to COVID-19 vaccinations. Nasal swabs from children living in households where their family members had varying levels of specific immunity to SARS-CoV-2 were collected.

Scientists easily detected the presence of SARS-CoV-2-specific IgG in nasal swab samples taken from children living in vaccinated households. Importantly, some of the nasal swabs obtained from children living in unvaccinated households revealed an absence of SARS-CoV-2 specific antibodies. The researchers compared SARS-CoV-2-specific IgG levels from nasal swab samples obtained from the two groups of children, i.e. living in vaccinated or unvaccinated households.

In this study, the authors used variation in parental intranasal IgG levels as the basis for stratification across all child samples. They used data from thirty-four adult-child pairs and established antibody cutoff values ​​for high and low parental intranasal antibody levels. They reported elevated levels of intranasal IgG in vaccinated parents, associated significantly with a 0.38 increase in log-transformed intranasal IgG gMFI, in a child from the same household.

Consequences

The authors of this study suggested that the transmission of antibodies by aerosol could contribute positively to the protection of the host against SARS-CoV-2 infection. The finding of the present study points to the role of passive immune protection in protecting individuals against disease. The researchers said that although the levels of antibody transfer required for host protection remain to be explored in the future, any amount of antibody transfer will benefit the recipient host.

According to a recent study, parental vaccination significantly reduced the risk of COVID-19 infection in unvaccinated children present in the same household. The authors of the current study believe that the above observation may be due to aerosol transfer of antibodies between vaccinated parents and unvaccinated children in the same household.

*Important Notice

medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be considered conclusive, guide clinical practice/health-related behaviors, or treated as established information.

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