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(Adds details on class of vaccines)
By John Miller
ZURICH, April 20 (Reuters) - A German scientist studying
extremely rare blood clots linked to AstraZeneca's
COVID-19 vaccine said on Tuesday Johnson & Johnson has
agreed to work with him on the research after similar serious
side effects emerged in recipients of its shot.
Andreas Greinacher, a transfusion medicine expert at
Greifswald University, announced the collaboration after the
European Medicines Agency said it would add a label to J&J's
vaccine warning of unusual blood clots with low platelet counts.
AstraZeneca's shot has a similar warning.
As with AstraZeneca, the EMA said benefits of getting J&J's
shot still outweigh the clotting risk, a position Greinacher
backs, too.
Greinacher, who on Tuesday released a new paper https://www.researchsquare.com/article/rs-440461/v1
offering a potential explanation for the complications, wants
J&J vaccine samples to study in his lab. Since mid-March his
team has been analyzing specimens from people who suffered clots
after getting AstraZeneca's shot.
"We agreed today with (J&J) that we will work together,"
Greinacher said during a news conference. "My biggest need,
which I've expressed to the company, is I would like to get
access to the vaccine, because the J&J vaccine is not available
in Germany."
Johnson & Johnson did not immediately respond to a request
for comment.
The EMA said on Tuesday it suspects the vaccine may trigger
an unwanted immune response, but safety committee chairwoman
Sabine Straus said it has not identified specific risk factors.
"It would be very helpful if we know beforehand, whether it
might be some kind of genetic disorder, or something else in the
blood vessels," Straus told reporters.
Greinacher does not believe such a prognostic test is
likely, based on experience with a similar disorder called
heparin-induced thrombocytopenia that has defied efforts to
identify why some people may be predisposed to the serious
condition.
"We even completely gene-sequenced 3,000 of these patients,
and we couldn't find a genetic predisposition," he said.
In Greinacher's new, not yet peer-reviewed, paper he
suggests the technology behind AstraZeneca's shot, some of its
ingredients and the powerful immune reaction it induces, may
contribute to a cascade of events that overpowers numerous
mechanisms that normally keep the human immune system under
control.
Health regulators and scientists are exploring whether the
clotting problem may affect the whole class of so-called viral
vector vaccines, which EMA's Straus said was possible while
noting differences in the two shots.
Both the AstraZeneca and J&J vaccines use a common cold
virus, albeit different ones, to ferry instructions to cells to
produce an immune response. J&J's shot uses a human adenovirus,
while AstraZeneca uses a chimpanzee adenovirus.
"Individuals are different, and only if by coincidence, nine
or 10 weaknesses are coming together, then we have a (problem),"
Greinacher said. "Otherwise, our in-built security systems block
it, and keep us safe."
(Reporting by John Miller in Zurich and Julie Steenhuysen in
Chicago; Editing by Bill Berkrot)
