Living with a COVID-19 case brings worse symptoms and a stronger antibody response

2019 Heterogeneous Coronavirus Disease (COVID-19) is caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), which was first detected in Wuhan, China in late December 2019.SARS-CoV-2 infections are very high differently. It is believed that the level of SARS-CoV-2 virus exposure may contribute to the severity of the disease.

Virus exposure includes the amount of virus inoculum, closer contact, and prolonged exposure. Greater disease severity may be associated with more robust antibody responses in the convalescence phase of the infection.

In a recent study, researchers found that people who lived with people who suffered from COVID-19 had greater severity of symptoms and stronger antibody responses. A greater degree of clinical manifestation and immune response was noted compared to individuals who were seropositive but did not live with a known case of COVID-19.

This study suggests that high virus exposures contribute to greater disease severity and stronger antibody responses. The observations from this study are published on the medRxiv * preprint server.

“Exposure to SARS-CoV-2 in the household can last longer compared to temporary public exposures, be physically nearby and cannot be reduced by personal protective equipment.”

Such a relationship between exposure dose and subsequent disease severity has previously been demonstrated experimentally for other respiratory viruses such as influenza, a respiratory disease. In addition, it has also been shown that the higher SARS-CoV-2 viral load during an acute infection in humans has been associated with a greater severity of the disease.

Associations between a roommate's exposure to Covid-19, symptom severity, and SARS-CoV-2 antibody levels.  The y-axis for SARS-CoV-2 IgG concentrations is shown on a log2 scale.  The data come from a community-based sample of seropositive adults from the Chicago area (n = 1011).  The distribution for each category is represented by smoothed kernel density plots overlaid with box plots representing interquartile ranges.  This figure was created with the R package “ggplot2” (version 3.3.2).

Associations between a roommate’s exposure to Covid-19, symptom severity, and SARS-CoV-2 antibody levels. The y-axis for SARS-CoV-2 IgG concentrations is shown on a log2 scale. The data come from a community-based sample of seropositive adults from the Chicago area (n = 1011). The distribution for each category is represented by smoothed kernel density plots overlaid with box plots representing interquartile ranges. This figure was created with the R package “ggplot2” (version 3.3.2).

In a previous study, the researchers reported that people who reported more symptoms had higher levels of immunoglobulin G (IgG) antibodies in a community-based sample of seropositive adults.

The participants in this study were tested positive for SARS-CoV-2 in the SCAN study (Screening for Coronavirus Antibodies in Neighborhoods). Through various recruitment methods, participants were recruited from neighborhoods across the Chicago area and from employees of the Feinberg School of Medicine (FSM) at Northwestern University in Chicago.

To assess exposure to roommates with COVID-19, participants were asked the following question: “Has anyone in your household been notified by a health care provider since March 1, 2020 that they have or likely to have COVID-19? Not receiving it in answering this question. “The median date of enrollment in the study was October 23, 2020 (range: June 30, 2020 to January 20, 2021).

“The results of our study show the importance of comprehensive sampling strategies that capture an appropriate range of variation in the context of exposure, symptom severity, and acquired immunity.”

This is an important study in which the researchers confirmed that those who were seropositive who lived with a COVID-19 roommate had a significantly higher level of symptom severity and IgG antibody responses than those who were seropositive who did not live with COVID -19 reported. This study reported that working near others showed no statistically significant associations with symptom severity or IgG antibody levels.

Specifically, the researchers indicated that this study design does not determine whether the roommate diagnosed with COVID-19 was the first case of SARS-CoV-2 exposure in the household. Future studies are needed to track the sequence of seroconversion and the onset of symptoms – to determine whether study participants may have been exposed prior to cohabitation.

As discussed in the study, the observations here underscore the importance of preventing transmission within households – to lower the rate of symptomatic COVID-19. As a critical focus for public health efforts, policies and interventions must include measures to reduce transmission in households (e.g., intensive testing, contact tracing, and isolation programs).

Even when people are isolated, if roommates develop symptoms of COVID-19, it is shown that high levels of SARS-CoV-2 virus shedding occurs before symptoms appear. Isolating people living in a household may not be achievable in many situations. As with other household respiratory virus exposures (such as the measles epidemics), preventing transmission in a household should become a critical focus to reduce SARS-CoV-2 transmission and COVID-19.

This study also sheds light on the effects of exposure dose and evaluates possible changes in vaccination strategies. Robust immune responses are observed after a single dose of an mRNA vaccine in seropositive individuals who have had milder disease or lower levels of pre-vaccination antibodies that were due to a previous natural infection.

The results of this study demonstrate the importance of comprehensive sampling strategies that capture a reasonable range of variations in exposure context, symptom severity, and acquired immunity, the researchers write.

Journal reference:

  • Household SARS-CoV-2 exposure is associated with higher symptom severity and stronger antibody responses in a community-based sample of seropositive adults, Joshua M. Schrock, Daniel T. Ryan, Rana Saber, Nanette Benbow, and Lauren A. Vaught Nina Reiser , Matthew P. Velez, Ryan Hsieh, Michael Newcomb, Alexis R. Demonbreun, Brian Mustanski, Elizabeth M. McNally, Richard D’Aquila, Thomas W. McDade, medRxiv 03/11/2021.21253421; doi: https://doi.org/10.1101/2021.03.11.21253421, https://www.medrxiv.org/content/10.1101/2021.03.11.21253421v1

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