Recently, the National Covid-19 Immunisation Programme (PICK) coordinating minister touched on the cocktail vaccines approach, with AstraZeneca as the first dose, and Pfizer-BioNTech as the second dose while speaking at a webinar organised by the Oxford and Cambridge Society of Malaysia.

Khairy Jamaluddin was answering a question from one of the listeners who asked if Malaysia plans to give Pfizer as the second dose to those who have taken the AstraZeneca as the first dose, given that it has extremely low efficacy rate against the Beta variant of Covid-19.

The Science, Technology, and Innovation Minister said that the proposal to employ the heterologous vaccination method was presented by Institute of Clinical Research (ICR) director Dr P Kalairasu.

How many countries have given a green light to mixing vaccines and how many are weighing such a solution?

  1. Bahrain: Eligible candidates could receive a booster shot of the Pfizer-BioNTech, or the Sinopharm vaccine regardless of which initial shot they have taken
  2. Canada: The country’s National Advisory Committee on Immunization has said that people who received the initial AstraZeneca shot could choose to receive a different vaccine for their second dose.
  3. Italy: Italy’s medical agency AIFA had said that people under the age of 60 who were inoculated with a first dose of AstraZeneca shot can receive a different second shot.
  4. Russia: The Interfax news agency reported that Russia may start trials on Covid-19 vaccine by combining its Sputnik V vaccine and various Chinese vaccines in Arab countries.
  5. South Korea: South Korea said that some 760,000 people who received the first shot of AstraZeneca will receive Pfizer’s jab as a second shot due to shipment delays.
  6. Spain: Its health minister said Spain would allow people under 60 who were inoculated with a first dose of AstraZeneca to get a second dose of either the AstraZeneca or Pfizer vaccine.
  7. United Arab Emirates: The UAE have made Pfizer-BioNTech coronavirus vaccine available as booster shot to those who initially immunised with a vaccine by Sinopharm. However, a representative of Mubadala Health, part of the state fund said that a different vaccine could be provided as a booster shot but this was at the recipient’s discretion and health professionals did not make recommendations.  
  8. United Kingdom: UK will take part in a mix-and-match vaccine trial to test the use of an additional vaccine dose from a different producer as a booster.
  9. United States:  The US National Institutes of Health (NIH) said that it had started a clinical trial on fully vaccinated adults to evaluate the safety and immunogenicity of a booster shot of a different vaccine.

Is mixing Covid-19 vaccines safe?

According to results from a Spanish trial with more than 600 people, giving Pfizer as a second dose after the first AstraZeneca shot produced a ‘robust immune response’ to Covid-19. Similarly, results from a German study also showed similar outcome. While research into mixing Covid-19 vaccines is still in its early stage, however, according to ABC report, the result is so far promising. According to the report, Cassandra Berry, a professor in immunology at Murdoch University said, “Vaccines are like a personal trainer for our immune system, and instead of making us train for a sprint race, we really want to train want to train to ensure and ultramarathon.” 

The first shot of AstraZeneca vaccine, followed by Pfizer as a second dose produce a ‘robust immune response’ to Covid-19, according to studies by Spain and Germany.
The first shot of AstraZeneca vaccine, followed by Pfizer as a second dose produce a ‘robust immune response’ to Covid-19, according to studies by Spain and Germany.

Albeit researches have shown good results so far, there still more to do before such an approach becomes a routine. More findings are needed to understand the effectiveness of using more than one vaccine. Prof David Taylor, emeritus professor of pharmaceutical and public health policy at University College London said that the vaccine’s concoction is inherently a good idea if one is worried about the efficacy.

“As the variants change, we’ll be introducing new antigens. It would be a sensible thing to do as and when a complementary vaccine becomes available. But we need data, we need trials,” he was quoted saying by The National News.

However, Dr Raghib Ali director of the Public Health Research Centre at New York University Abu Dhabi has noted that at least one study has indicated a higher rate of side effects in people that are given different Covid-19 vaccines. Symptoms such as fever ad headaches may be more common. Prof Zhou Xing, of the McMaster Immunology Research Centre at McMaster University, Canada, has said that the results from a study conducted by Spain and Germany are both encouraging. He further suggested that through the experiences gained during the pandemic in using more than one vaccine may offer wider benefits into the future.