Picture: 123RF/S SILVER
Picture: 123RF/S SILVER
Image: 123RF/S SILVER

London — When it comes to their own health, some in the pharma industry aren’t waiting for governments to tell them they can mix two different Covid-19 vaccines.

While research is still under way on the effects of taking mismatched shots, some people who’ve studied the science are switching up their doses to get what they claim is better protection. At least one industry veteran even crossed borders to do it.

“If you prime the immune system with a certain technology, you get a broader, higher and more lasting response if you boost with something aiming at the same target but based on a different technology,” said Pierre Morgon, who sits on the board of companies including Vaccitech and Univercells.

After years of reading research on mixing vaccine types — known as heterologous prime-boosting — Morgon concluded that getting one dose of the AstraZeneca shot, which uses a harmless virus as a vector, and another from Moderna’s or Pfizer’s newer messenger RNA technology would pack the most punch. Broadening immunity has become especially important as variants show some ability to evade vaccines.

In April, Morgon drove a couple of hours from his home in Lausanne, Switzerland, to a pharmacy in Lyon, France, for an Astra shot. He followed up in Switzerland almost eight weeks later with a dose of Moderna’s vaccine.

Karine Van Hasbrouck, a former marketing executive at French pharma giant Sanofi, received the same mix as Morgon. The combination “looks very promising in terms of immune response,” she wrote on LinkedIn. She declined to comment further.

Mix-and-match dilemma

For now, taking two different shots is likely to remain the exception rather than the rule, even as some countries explore the approach. Most of the vaccines in use require two doses of the same product. France, Spain, Finland, Sweden, Norway, and Canada are mixing vaccines or considering it among some age groups who had already received an Astra shot for their first dose, because of concern over rare blood clots linked to that vaccine.

Those countries’ decisions were emergency ones, but may leave patients better off.

“If you can mix and match, it’s going to look better, something that immunologists have known for decades,” said Danny Altmann, professor of immunology at Imperial College London. “I’d bet my house on the working hypothesis that it’s doable and would produce immunity that’s at least as good if not better.”

Early research appears to back the approach. A study of almost 700 people in Spain showed that those who received a second dose of Pfizer’s vaccine after a first Astra shot saw their neutralising antibodies climb sevenfold, significantly higher than those who had two Astra doses.

A small trial in Germany suggested that mixing Astra and Pfizer shots could trigger antibody responses almost four times higher than a two-dose course of the Pfizer vaccine. Researchers are also looking at mixing Astra’s shot with the Sputnik V vaccine among trial participants in Russia, Azerbaijan, Belarus and the United Arab Emirates.

Side effects

In the US, the National Institutes of Health recently launched a trial to evaluate the method in humans, suggesting an approval for the general population could still be several months away.

One drawback is that the approach appears to cause more side effects such as fevers, chills and headaches, according to researchers at the University of Oxford.

That didn’t stop Bill Enright, the Maryland-based CEO of Vaccitech, the British firm that designed the technology behind AstraZeneca’s shot.

Because the Astra shot isn’t yet approved in the US, Enright got Johnson & Johnson’s vaccine, which uses similar technology but is intended for a one-dose regimen. He followed up three months later with a dose of the vaccine developed by Pfizer and BioNTech, and said he didn’t have any significant side effects.

“They asked ‘why are you getting a booster?’ And I said ‘this is what I do for a living.’ And they said, ‘OK’,” said Enright, who got both jabs in the US. “I think we’ll get a stronger immune response, a stronger protection against existing and variant strains and likely a longer immunity.”

Bloomberg News. More stories like this are available on bloomberg.com

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