(upbeat music)
- [Narrator] Chinese COVID-19 vaccines are being used
in dozens of countries.
- China has donated vaccines everywhere
for those countries who need help.
- [Narrator] But these shots have some
of the lowest efficacy rates
among globally used coronavirus vaccines,
ranging between 50 to nearly 80%.
Compare this with shots from Pfizer-BioNTech, Moderna
and Russia's Sputnik V.
The head of China CDC in early April said the efficacy
of some vaccines was not high.
And this also included ones from his own country.
So China is looking to bolster the protection rate
and one way is to mix and match different types of vaccines.
And this idea isn't new.
- We really welcome studies
that would look at mix and match regimens.
- [Narrator] Spain is also interested in combining vaccines
while researchers in the UK
and Russia are already studying this.
So as China joins the ranks
of countries looking to mix and match,
here's how it can be a key
to overcoming multiple vaccination challenges at once.
Most Chinese vaccines and other shots currently in use
require two doses, creating an opportunity to mix and match.
Some immunologists believe this could have a number
of benefits like boosting the immune response.
- The theory is that if you train the immune system
to recognize a virus in a slightly different way each time,
then you might get a broader
and more durable immune response.
- [Narrator] And a more robust immune response
is important since China has confirmed cases
of new and more transmissible variants
that were first identified in the UK and South Africa.
Mixing and matching for this reason has gotten support
from at least one Chinese drug maker so far.
Some immunologists also say
that mixing and matching could ease the pressure
from the vaccine supply chain.
So for example,
in countries that are rolling out Chinese vaccines
along with other supplies,
using two different shots could give doctors more options
when patients come in for the second dose.
But one of the most important reasons
is when there are severe side effects
from one of the vaccines.
- If someone perhaps has a strange
or severe allergic reaction to the first shot that they get,
perhaps then you could avoid that
by giving them the second dose from a different vaccine.
- [Narrator] The idea became particularly important
after regulators started investigating
rare blood clotting disorders linked
to AstraZeneca's COVID vaccine.
As of late March, 79 people in the UK
have had severe blood clots
out of the 20 million administered doses
of AstraZeneca's vaccine.
In France and Germany,
health authorities are advising younger people
who have received a first dose of AstraZeneca
to get a second dose of a different vaccine.
The drug maker said it's working with health regulators
and starting the rare blood clotting events
and possible causes.
While these upsides could bring China and other countries
closer to getting their population vaccinated,
health authority say there's still a lot to learn
about possible side effects or how it may affect efficacy
of the vaccines, especially when it comes
to combining shots made with different technologies.
- The vaccine, such as Chinese vaccine
and the vaccines by AstraZeneca and Johnson & Johnson
are vaccines that use a virus as the vector
to get the genetic instructions into your body.
- [Narrator] Whereas Pfizer-BioNTech and Moderna vaccines
use a new gene-base technology involving messenger RNA,
where molecules carry genetic instructions.
- So we're not too sure what happens
when you mix these two technologies together.
- [Narrator] Chinese health authorities have said people
can receive different brands that use the same technology,
but don't recommend mixing vaccines
with different technology so far.
But now trials with the combination
of two homegrown vaccines with different technologies
are underway in China with more than a hundred volunteers.
The country is also working on its own mRNA vaccine
and looking closely at approving Pfizer-BioNTech shot,
according to people familiar with the matter.
This would pave the way for China to mix and match
its more conventional vaccines with mRNA shots.
Similar to how researchers in the UK are studying
the combination of AstraZeneca
with Pfizer-BioNTech or Moderna.
Those results are expected as early as may
- Immunologists, when you speak to them
about this sort of process, are pretty enthusiastic about it
and optimistic that it's going to work.
But that's maybe the one big drawback
is we want to make sure that it works,
we want to make sure that it isn't worse,
you don't get a worse immune response
than if you had two doses of the same vaccine.
(gentle music)