Page 11 - April-May 2020 Neat
P. 11
Coronavirus Immunity & Antibodies 11
Everything we know
about coronavirus
immunity and antibodies
— and plenty we still
don’t
Continued from Page 10
Scientists who have looked at antibodies to
other coronaviruses — both the common-cold
causing foursome and SARS and MERS —
found they persisted for at least a few years,
indicating people were protected from
reinfection for at least that long. From then,
protection might start to wane, not drop off
completely.
The experience with other viruses, including the
other coronaviruses, has encouraged what
Harvard epidemiologist Marc Lipsitch summed
up as the “educated guess” in a recent column in
we are early in this outbreak and survivors from But one preprint released this month
the New York Times: “After being infected with
the first weeks of infection in China are, at complicated the landscape. (Preprints have not
SARS-CoV-2, most individuals will have an
most, only three months since recovery,” the been peer-reviewed or published yet in a
immune response, some better than others. That
report said. research journal.) Researchers in Shanghai
response, it may be assumed, will offer some
reported that of 175 patients with confirmed
protection over the medium term — at least a Covid-19, about a third had low antibody levels
year — and then its effectiveness might What else can antibody tests show?
and some had no detectable antibodies. The
decline.”
In addition to identifying those who have been findings suggest that the strength of the antibody
But many serological tests aren’t like pregnancy infected, antibody tests can also suggest at a response could correlate to the severity of
infection, though that’s not known for sure.
tests, with a yes or no result. They will reveal broader level how widely the virus has spread. They also raised concerns that those with a
the levels (or titer) of antibodies in a person’s These data have implications for how severe weaker antibody response might not be immune
blood. And that’s where things can get a bit future outbreaks of cases might be and what from reinfection.
trickier. At this point, scientists can’t say for kind of restrictions communities might need to
sure what level of antibodies might be required live under. If more people have been infected But outside researchers have said that
for a person to be protected from a second than known — a strong likelihood, given the conclusions about immunity can’t be drawn
Covid-19 case. They also can’t say how long number of mild infections that might have been from what the study found. For one, there are
people are safeguarded, though it’s thought that missed and testing limitations in countries different kinds of antibodies, so some might
a higher initial titer will take longer to wane including the United States — then more people exist that the test wasn’t looking for. Secondly,
than low levels. are thought to be protected going forward.
studies in other coronaviruses have shown that
“Further investigation is needed to understand In the United States, the Centers for Disease antibody responses vary from person to person,
without clear implications for how protected
the duration of protective immunity for SARS- Control and Prevention and the National someone is from another infection.
CoV-2,” a committee from the National Institutes of Health have both launched
Academies of Sciences, Engineering, and “serosurveys” to assess how many people might And, researchers say, antibodies are not the only
Medicine wrote in a report this month. have contracted the virus. Even employees of
Major League Baseball teams have been trick the body has to protect itself. Immune cells
It’s not just whether someone is immune enlisted in a study enrolling thousands of also form memories after an initial infection and
can be rallied quickly should that same pathogen
themselves. The next assumption is that people patients.
try to strike again, even without antibodies or
who have antibodies cannot spread the virus to after antibody levels fade.
others. Again, that hasn’t been shown yet. What have data from serosurveys
shown thus far about antibody
“People that lose that serum neutralization — it
“We don’t have nearly the immunological or generation? doesn’t mean necessarily that they’re not going
biological data at this point to say that if
to have some level of immunity,” said virologist
someone has a strong enough immune response A number of countries have launched large Vineet Menachery of the University of Texas
that they are protected from symptoms, … that serosurveys, so hopefully we’ll have a better Medical Branch. “Your immune system hasn’t
they cannot be transmitters,” said Michael sense soon of the levels of antibodies being forgotten. It may just take them a couple of days
Mina, an epidemiologist at Harvard’s T.H. Chan generated by individuals who recover from to generate that immune response and be able to
School of Public Health. Covid-19 and among the general population. clear a virus.”
For now, though, there have only been limited
The challenge, as the National Academies data released from a couple small studies. He added that it’s likely that if and when
report highlighted, is that no one knew about
protection starts to wane and people contract the
this virus until a few months ago. That means Scientists in Europe have pointed to strong coronavirus a second time, it’s likely to cause an
they haven’t been able to study what happens to antibody production in patients within a few even milder illness. (Continued on Page 13)
people who recover from Covid-19 — and if weeks of infection. One study found that people
and how long they are protected — for more were generally quick to form antibodies, which
than a short period of time. could help explain why the majority of people DARE TO BELIEVE
do not develop severe cases of Covid-19. DARE TO BE HEARD!
“One key uncertainty arises from the fact that www.XZBN.net
