February 2022, ScientificAmerican.com 65mRNA vaccines found that vaccination was 77 per-
cent effective against hospitalization with COVID,
compared with 90 percent for immunocompetent peo-
ple. But the effectiveness ranged widely depending on
the immune condition, from 59 percent for organ or
stem cell transplant recipients to 81 percent for peo-
ple with a rheumatological or inflammatory disorder.
Dorry Segev, a professor of surgery at Johns Hopkins
University, and his colleagues have been studying how
well transplant recipients and others with suppressed
immune systems respond to the COVID vaccines. In
June 2021 he and his team published a study in JAMA
showing that out of more than 650 transplant recipi-
ents who received an mRNA COVID vaccine (either Pfiz-
er’s or Moderna’s), 46 percent had no detectable re -
sponse after one or two doses; 39 percent did not have
a response to one dose but did after a second. In a sep-
arate study, they found that transplant recipients who
received the Johnson & Johnson vaccine were much less
likely to have a detectable response than those who had
an mRNA vaccine. This lack of protection could be dan-
gerous: Segev and his colleagues found that vaccinated
recipients were 82 times more likely to have a break-
through infection than the general population and 485
times more likely to be hospitalized and die from it.
Also in June, Segev and his colleagues published
a study online in the Annals of Internal Medicine of
30 transplant recipients who received a third dose of
a COVID vaccine. Six of the patients had low but
detectable antibody levels after their initial two shots,
and 24 had no detectable antibodies. Of those who
had low antibody levels, all six had high levels after
the third dose. But only six of those who had no anti-
bodies had high antibody levels after a third dose.
These findings helped to form the basis of the cdc’s
decision last August to make a third dose available to
immunocompromised people, before booster shots
were authorized for all adults. In some people—mostly
those with autoimmune diseases—“a third dose helps
a lot and gets them over that hump to a more protected
level of antibody,” Segev says. Most transplant recipi-
ents, however, have not been as fortunate. “Only a frac-
tion of transplant patients who got a third dose reach
that kind of a milestone.” For people who get vaccinated
while waiting for a transplant, however, there is good
news. “They will likely have a very, very good vaccine
response—way better than they’ll get once they’re on
immunosuppression,” Segev says.
Another highly vulnerable group is patients with
blood cancers, such as Powell. Nearly 35,000 people in
the U.S. are diagnosed with multiple myeloma every
year. The disease attacks bone marrow plasma cells,
which make antibodies in response to the virus that
causes COVID—and to the vaccines. Drugs prescribed
to treat it kill off normal plasma cells, as well as can-
cerous ones, further compounding the problem.TO PREVENT
his body from
reject ing the donor
organ, Franklin
takes immuno
suppress ive
medi cation, but
it also makes
him vul ner able
to COVID and
other infections.