Immunity?

Regarding "Immunity Passports" Thu 18 Jun 2020

Source: Newsweek

https://www.newsweek.com/coronavirus-antibodies-lost-10-wuhan-study-patients-within-21-days-1511850

Chinese scientists have cast doubt over whether we have long-lasting

immunity to the coronavirus in 2 studies released this week, prompting

them to question the use of immunity certificates.

[...]

According to the scientists, the around 10% of COVID-19

patients in their pre-print study who didn't have antibodies 21 days

after their symptoms started likely "lost" them after they recovered.

In contrast, patients with severe acute respiratory syndrome (SARS)

have been known to carry antibodies for up to 210 days, the researcher

said.

[...]

They said, "Very few healthcare

providers had IgG [virus-specific] antibodies to SARS-CoV-2 [the

COVID-19 coronavirus], though a significant proportion of them had

been infected with the virus. After SARS-CoV-2 infection, people are

unlikely to produce long-lasting protective antibodies against this

virus."

[...]

Symptomatic patients had significantly higher levels of virus-specific

antibodies than the asymptomatic during the period when the virus

could still be detected in their respiratory tracts. Eight weeks after

the patients were discharged from hospitals, 81% of asymptomatic

patients saw levels of their neutralizing antibodies drop compared

with 62% of symptomatic patients.

[...]

Echoing their concerns, the medRxiv researchers said, "As infected

people do not develop long-lasting protecting antibodies against

SARS-CoV-2, the idea of immune certificate for recovered COVID-19

patients is invalid."

Weak immune response in asymptomatic cases

Date: Fri 19 Jun 2020

Source: Genetic Engineering & Biotechnology News
https://www.genengnews.com/news/asymptomatic-covid-19-cases-may-have-weaker-immune-responses/

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. [,,,]