With new guidelines following reports of rare blood clots, the global medical community is evaluating whether it is possible and safe to give two different vaccine candidates to the same person.

This week, the European Medicines Agency and the UK Medicines and Health Products Regulatory Agency found a possible link between the AstraZeneca University Oxford vaccine and very rare cases of unusual blood clots with low platelets.

Neither the European nor the UK health authorities recommended age restrictions on the use of the vaccine. However, the UK regulator noted that the data suggests a slightly higher incidence is reported in the younger age groups of adults, so recommends that these evolving findings be taken into account when using the vaccine.

The EMA also reiterated that the vaccine is safe and effective, but noted that the use of the vaccine at national level will also take into account the pandemic situation and availability of vaccines in each country.

As a result, the UK, various EU countries and other governments around the world have recommended the use of alternative vaccines for younger people.

With the change in guidelines, younger people are now asking, if I’ve already had one dose of the vaccine, should I come back for the second?

Governments have different answers to this question. Health professionals generally agree that mixing and matching vaccines should be safe. However, clinical studies are still ongoing.

Instructions vary

The UK Joint Committee on Vaccination and Immunization advises: “Anyone who has received a first dose of the AstraZeneca COVID-19 vaccine, regardless of age, should continue to be offered a second dose of the AstraZeneca COVID-19 vaccine. The second dose will be important for longer lasting protection against COVID-19. “

In contrast, the French health authority recommends that people under the age of 55 who received their first dose of AstraZeneca should be given Pfizer or Moderna for their second shot. In these cases, a break of 12 weeks between these first and second recordings is recommended. The regulator stated that if you had the first AstraZeneca burst and then switched to an mRNA burst for the second, there was no reason to fear certain adverse events.

Germany followed a similar path. The German vaccine committee recommended people under 60 who had received a shot of AstraZeneca jab to opt for a different vaccine for their second dose.

The Prime Minister of Baden-W├╝rttemberg, Winfried Kretschmann (R), will receive the AstraZeneca vaccine against the novel corona virus in Stuttgart on March 19, 2021.

MARIJAN MURAT | AFP | Getty Images

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“The guidelines are the guidelines. But, as a basic immunologist, can I see an argument as to why it would be unsafe or bad to mix and match vaccines? No, I can’t see any at all. It would still produce great immunity. None Problem with that, “Danny Altmann, professor of immunology at Imperial College London, told CNBC’s” Squawk Box Europe “on Friday.

Andrew Freedman, an infectious disease reader at Cardiff University’s School of Medicine, told CNBC, “Studies are currently underway to examine the concept of mix and match. There is no theoretical reason why this should not be feasible or safe, but we have to wait for these studies. “

Regarding a possible booster dose that might be needed in the fall or winter, he added, “I don’t think there is any real concern that you would not be able to take two doses of the AstraZeneca vaccine with either of the others administer messenger RNA vaccines. ”

Meanwhile, Franz-Werner Haas, CEO of vaccine maker CureVac, told CNBC this week, “The good news is that all of these vaccines code for the same spike protein, so there are clinical trials and data that you mix and match mix can fit these different vaccine platforms. ”

“In that regard, I have high hopes that this will work out quite well,” he added.

CureVac’s own candidate is still in clinical trials. The data read is on track for the second quarter of this year.

The Centers for Disease Control and Prevention claim that the safety and effectiveness of a mixed line of products have not been rated.

Several studies are examining the effects of mixing vaccines. The UK started a study in February that specifically mixed the AstraZeneca-Oxford vaccine with the Pfizer BioNtech shot. The results are not expected to be available until summer. Independently of this, studies are carried out in which a combination of the vaccines AstraZeneca-Oxford and Russian Sputnik V is examined.