Studies have shown that SARS-CoV-2 infection is four times more likely to be transmitted at home than in the community.

A group of researchers across the United States working with their Swiss counterparts to understand the infectious dynamics of the new drug that causes coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS CoV-2). We conducted an extensive population-based serological survey. Illness 2019 (COVID-19).

Their study, entitled “Home Infection of SARS-COV-2: Insights from Population-Based Serological Surveys,” is available on the preprint server site. medRxiv.. *

Research background and need

Since its first appearance in Wuhan, China in late December 2019, more than 50 million people worldwide have been infected with SARSCoV-2.

Therefore, people who have contact with the infected person at home are at increased risk of being infected with the virus. Therefore, studies investigating viral infections within domestic contacts are essential for a better understanding of COVID-19 infections.

Currently, studies investigating domestic COVID-19 infections are being conducted to detect contact-based infections using the reverse transcription polymerase chain reaction test (RT-PCR), a nuclear-derived method that can detect the presence of SARS-CoV-. Depends on. Two genetic material in the host cell. This is currently the most common test format and is usually performed using a nasal swab sample. People who are currently in contact with individuals who are mildly symptomatic or asymptomatic are tested for RT-PCR because of the limited time frame in which virological testing can give positive results. May be overlooked at. The authors of the study explain that these restrictions can underestimate actual mild or asymptomatic cases among household contacts and miscalculate the secondary incidence of households. ..

Serological survey

Serological studies look for the presence of antibodies to SARS-CoV-2 in human blood. Researchers suggest that this form of testing may be an effective alternative to detecting the spread of the virus among household contacts. For one thing, these serological tests give positive results for infected individuals for longer periods of time compared to RT-PCR testing.

A recent large-scale meta-analysis of other studies shows that the secondary incidence rate in the home is about 17 percent. Therefore, research misses some aspects of estimating home infection rates and helps fill knowledge gaps. This study was conducted using a serological study.

Frequency of households of different sizes in the study (A), proportion of seropositive people by house size (B), and distribution of the number of seropositive people in households by size (C).

Importance of this study

This study was conducted to determine asymptomatic infections in COVID-19 patients and the transmission of infections through contact with home and community. This will help understand and design ways to control the spread of the infection, the researchers wrote. Serological studies have helped detect all previously infected individuals, the team writes.

Study design

This is a SEROCoV-POP study, a population-based study of individuals aged 20-74 from Geneva, Switzerland (Canton).

All participants in the study (10,587 in total) were invited to participate in the serological study. Participants were asked to bring the entire family over the age of five. Since January 2020, in-household and out-of-household contacts have been considered.

All participants and home contacts in the study were asked about symptoms such as coughing, fever, shortness of breath, or odor or loss of taste from January 2020 to 2 weeks before the serological blood test. For all participants, anti-SARS-CoV-2 IgG antibody was detected using an enzyme-linked immunosorbent assay (ELISA) test.The antibody was against the S1 domain of Spike protein Of SARS-CoV-2.

The team used a chain binomial model to assess the number of infections that spread within the household and estimate the risk of infection within and outside the household.

result

The survey involved a total of 4,524 household members aged 5 and over from 2,267 households between April and June 2020. The median age was 53 years and 53.6% of the participants were women. The overall result is as follows:

• The risk of infection from contact with a single infected household was 17.2 percent (95% CrI 13.6-21.5 percent).
• The risk of infection from out-of-household contact was 5.1% (95% CrI 4.5-5.8%).
• As we grew older, the risk of infection from contact with the home increased from 7.5% (95% CrI 1.3-20.3%) to 30.2% (95% CrI 14.3-48.2%) in children aged 5-9 years. .. 65 years old.
• The risk of infection from out-of-household contact was highest among individuals in the working-age population between the ages of 20 and 49.
• Contacts in households that are antibody-positive but not symptomatic of COVID-19 are 74.8% less likely to infect another household member than positive contacts with symptoms (19.6% 95%) (95%). % CrI 43.8-90.3%). CrI 12.9-24.5%).

Conclusions and implications

This study shows that the risk of contracting SARS CoV-2 after exposure to a single infected household member is four times higher than the risk of active external contact. The team noted that younger children are less at risk of transmission from home contact than older children, and asymptomatic cases are less likely to spread to domestic contact. The authors write that “small households in Geneva limit the contribution of household expansion, but household propagation is likely to play a greater role in other situations.”

*Important Notices

medRxiv Publish preliminary scientific reports that should not be considered definitive as they are not peer-reviewed, guide clinical / health-related behaviors, and should not be treated as established information.