Weak immune response in asymptomatic cases
Date: Fri 19 Jun 2020
Source: Genetic Engineering & Biotechnology News
Asymptomatic COVID-19 Cases May Have Weaker Immune Responses
[...]
...other infections remain
asymptomatic. Neither the clinical features nor the immune responses
of asymptomatic cases have been well described.
[...]
. Now, a small study performed by a group from Chongqing
Medical University in Chongqing, China, found that people who fail to
develop COVID-19 symptoms may have a weaker immune response to the
virus. They also found that people's antibody response to SARS-CoV-2
may diminish rapidly after infection, which may have implications for
the interpretation of negative serological results.
[...]
Of the 37 asymptomatic patients
-- identified in a group of 178 people with SARS-CoV-2 infection -- 22
were female and 15 were male, with ages ranging from 8-75 years
(median age, 41 years).
The authors found that these patients had a significantly longer
duration of viral shedding, with median duration of viral shedding of
19 days, compared with 14 days in a group of 37 symptomatic patients.
Levels of virus-specific IgG antibodies were significantly lower in
the asymptomatic group than in the symptomatic group during the acute
phase of infection, when the virus could be detected in the
respiratory tract.
Eight weeks after the patients were discharged from the hospital,
antibody levels were measured. Of asymptomatic individuals, 93.3% and
81.1% had a reduction in IgG and neutralizing antibody levels,
respectively, during the early convalescent phase, as compared to
96.8% and 62.2% of symptomatic patients.
In addition, asymptomatic patients had lower levels of 18 pro- and
anti-inflammatory cytokines. The authors suggest that this indicates
that the asymptomatic patients may have had a weaker immune response
to SARS-CoV-2 infection.
The authors also observed that IgG levels began to diminish within 2-3
months of infection in a large proportion of the asymptomatic
patients [...]
They argue that this finding, along with previous analyses of
neutralizing antibodies in patients recovering from COVID-19,
highlights the potential risks of using "immunity passports" and
supports the continuation of public-health interventions and
widespread testing. [,,,]