Potent Immune Response, Supply Shortage Have Pushed These Countries to Allow Mix and Match of Covid Jabs

Amid conjectures over the efficacy of mixing Covid-19 vaccines as the coronavirus continues to mutate and evolve, the Subject Expert Committee (SEC) of the Central Drugs Standard Control Organisation (CDSCO) told CNN-News that it is in favor of administering different doses of Covaxin and Covishield to people.

This will be the first mix and match study in India of the two indigenous vaccines, the clinical trial of which will be conducted by Christian Medical College (CMC) in Vellore.

Mixing and matching coronavirus vaccine shots refer to the process of administration of one brand of vaccine for the first dose and using a vaccine made by a different vaccine manufacturer for the second dose. As the Delta variant of coronavirus continues to rapidly spread and remerge across the world, lowering efficacy rates of available vaccines, experts opine that at a critical stage like this, mixing two vaccines, or opting for different doses of vaccines could potentially trigger higher efficacy, effectiveness, and immunity and lower any safety concerns which could be present with some vaccines.

The mix-and-match strategy is known as a heterologous prime and boost and has been used in the past against diseases such as Ebola and AIDS.

As India gears up for its first mix and match study, here is a look at some countries which have already allowed the mixing of two vaccines.

Canada

The North American country decided to vaccinate beneficiaries who have already got one dose of the AstraZeneca vaccine with the second shot of either Pfizer or Moderna. In a similar decision, the National Advisory Committee on Immunization also allowed beneficiaries who have been given the first dose of either Pfizer or Moderna to go with any during their second dose. The shortage of Covid vaccine has also fuelled this need.

USA

On 1st June, the US became the latest country to announce the beginning of clinical trials to test the use of different Covid vaccines in fully vaccinated adults as a booster shot. The trial results are expected in late summer 2021.

UK

In January, the British government stated that people may mix and match their two shots, in case they are unaware of the vaccine they received, or the vaccine they received as their first dose is not available. They also allowed for Pfizer and Moderna vaccines to be used interchangeably. An Oxford-University-led study found that beneficiaries who have been vaccinated with two different vaccines are more likely to face mild or moderate post-vaccination ailments in comparison to those who have been vaccinated with the same dose.

UAE

The United Arab Emirates has made the Pfizer/BioNTech coronavirus vaccine available as a booster shot to those initially immunised with a vaccine developed by the China National Pharmaceutical Group (Sinopharm).

Spain

In May the Spanish government allowed beneficiaries who have been vaccinated with AstraZeneca vaccine to opt for Pfizer vaccine as their second dose. However, the go-ahead was only been given to adults aged below 60 years. The Spanish government said that its decision was backed by a trial conducted by Carlos III Health Institute which found that the second dose of Pfizer after AstraZeneca was highly effective and safe.

Bahrain

Bahrain said on June 4 that eligible candidates could receive a booster shot of the Pfizer/BioNTech (PFE.N), or the Sinopharm vaccine, regardless of which shot they had initially taken after the island witnessed a spurt in Covid Cases.

Apart from these, France, Norway, and Sweden have also allowed those who have taken one dose of the AstraZeneca vaccine to take one of the approved mRNA vaccines as their second dose.

Among the countries still mulling over the mixing of two vaccine doese include, Russia and South Korea. As per sources, the Chinese government is also conducting studies and clinical trials before deciding on the issue. The Russian health authorities after giving initial go-ahead to mixing Sputnik V and AstraZeneca doses have now asked for more clinical data and put the decision on hold. France’s top health advisory body had recommended in April that people under 55 injected with AstraZeneca first, should receive a second dose with a so-called messenger RNA vaccine, although dose-mixing has not yet been evaluated in trials.

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