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By Nancy Lapid
March 3 (Reuters) - The following is a roundup of some of
the latest scientific studies on the novel coronavirus and
efforts to find treatments and vaccines for COVID-19, the
illness caused by the virus.
Immune system T cell responses to variants remain potent
While worrisome coronavirus variants identified in Brazil,
South Africa, and California have mutations that might help them
resist antibody treatments and vaccines, the immune system's T
cell responses to the variants are unaffected in recovered
patients and in people who have received the Moderna Inc
or Pfizer Inc/BioMTech SE vaccines,
new data show. "We think this is really good news," said
Alessandro Sette of the La Jolla Institute for Immunology, whose
team reported the findings on Monday on bioRxiv ahead of peer
review. The T cells induced by vaccines can recognize pieces of
the virus spike protein, while T cells induced by previous
infection recognize multiple parts of the virus, including the
spike and other proteins, Sette said. "These pieces are largely
not changed/mutated in the variants," he explained. "This means
that the T cell responses recognize the 'ancestral' sequence and
the variants equally well." While circulating memory T cells
would probably not prevent infection, they could reduce COVID-19
severity, he added. T cell responses are known to be linked with
milder COVID-19, he noted, and may contribute to limiting
COVID-19 severity induced by variants that partially or largely
escape neutralizing antibodies. (https://bit.ly/384IAMo)
Asthma does not increase COVID-19 risks
Asthma itself is not a risk factor for hospitalization or
more severe COVID-19, and people whose asthma is triggered by
allergies may actually be at lower risk, according to new
research presented at the American Academy of Allergy, Asthma
and Immunology virtual annual meeting. Researchers at Stanford
University studied 5,596 patients who tested positive for
COVID-19 from March to September 2020. Of these, 11% were
hospitalized, including 100 patients with asthma. After
accounting for patients' other medical conditions that have been
linked with more severe COVID-19 illness, including high blood
pressure, heart disease, diabetes and obesity, "asthma was no
longer a risk factor for hospitalization," said Dr. Lauren
Eggert. Among patients who were hospitalized, asthma was not
significantly associated with disease severity, she said.
Researchers also found that patients with allergic asthma were
nearly half as likely as patients with other types of asthma to
need hospitalization. A possible explanation, Eggert said, is
that in allergic asthma, the immune system "downregulates," or
reduces the production, of the ACE2 proteins on cell surfaces
that are a major port of entry for the coronavirus. (https://bit.ly/3reYR9j)
Antibodies to variants may offer cross-protection
Antibodies to a newer, more infectious coronavirus variant
might prevent infection by earlier variants, laboratory studies
suggest. In test tube experiments, researchers studied the
neutralizing effects of antibodies obtained from people infected
with COVID-19 in the first wave of the pandemic in South Africa,
when the initial version of the virus was predominant, and in
survivors from the second wave, when a more infectious,
harder-to-treat new variant predominated. First-wave antibodies
neutralized the first-wave virus but not second-wave virus. As
expected, second-wave antibodies neutralized second-wave
viruses. They also neutralized the first-wave virus, although
not as potently, according to a paper posted on Saturday on
medRxiv ahead of peer review. In a news conference on Wednesday,
co-author Alex Sigal from the Africa Health Research Institute
said the findings offer hope that vaccines based on the variant
could protect against this and other variants circulating
worldwide. Pfizer, AstraZeneca Plc, Johnson & Johnson
and Moderna are already developing vaccines based on the
variant identified in South Africa. Salim Abdool Karim, a top
government adviser on COVID-19, predicted that by the end of
2021 most vaccine manufacturers will have adapted their shots,
accordingly. (https://bit.ly/3rhXJSq; https://reut.rs/2MHJaZ8)
UK finds vaccines protect elderly
The Pfizer and AstraZeneca vaccines are more than 80%
effective at preventing COVID-19 hospitalizations in people over
age 80 after one dose, Public Health England said on Monday,
citing a study released on medRxiv ahead of peer review. The UK
study also found that in people over age 70, two doses of the
Pfizer vaccine are approximately 85% to 90% effective at
preventing symptomatic disease. Pfizer vaccine recipients in
that age group who did acquire symptomatic infections had a 44%
lower risk of hospitalization and a 51% lower risk of death
compared to unvaccinated patients. Because the two-dose
AstraZeneca vaccine had only recently been introduced,
researchers only had data after one dose. The effect against
symptomatic disease was approximately 60% to 75%, and there was
also a protective effect against hospitalization, the
researchers said. They noted that the AstraZeneca data was
gathered while a more-infectious variant was predominant in the
UK. Britain's use of the AstraZeneca vaccine on elderly people
contrasts with many European countries, which have cited a lack
of clinical trial data for their decision not to use it on older
people. (https://bit.ly/3rktaLW; https://reut.rs/3kKIEX4)
Open https://tmsnrt.rs/3c7R3Bl in an external browser for a
Reuters graphic on vaccines in development.
(Reporting by Nancy Lapid, Megan Brooks, Kate Kelland, and
Alexander Winning; Editing by Bill Berkrot)
