It seems that our pandemic struggle won’t end soon. Especially now with new waves of COVID variants and mutations rising in the background. For instance, the major concern right now is the newest highly transmissible SARS-CoV-2 virus strain which is the Delta Variant. With the continuous shortage on the global vaccine supply, the Delta variant will intensify the pandemic situation. This is no doubt to be true according to Yale Medicine epidemiologist F. Perry Wilson, MD. For this reason, many countries have resulted to their own inoculation strategies. One of these is the mixing of COVID vaccines in order to curtail the spread of COVID-19.
How are mixed jabs administered?
Primarily, mixing of COVID vaccines entail that a single person will receive his two doses with two different vaccines.
There is a myriad of studies that have attested that mixing of COVID vaccines could actually give a robust immune response. In fact, they call this trend as the heterologous prime-boost COVID-19 vaccination strategy.
In the United Kingdom, the University of Oxford has initiated a Com-COV study. This study investigates the response of people’s immune system. The study of Comparing COVID-19 Vaccine Schedule Combinations look into the effect of introducing one type of vaccine while having the second dose with another. Furthermore, the Com-COV study will also observe the immune response based on the span of inoculation between the first and the second dose. Moreover, the common vaccine reactions after the mixed schedules will also be taken into account. Lastly, this study will help hasten the immunization program as well as it will determine the flexibility of mixing of COVID vaccines. Above all, the study will give pertinent evidence about the efficacy of an extended gap between the prime dose and the booster dose.
“Mixing doses could provide us with even greater flexibility for a booster program. Likewise, supporting countries who have further to go with their vaccine rollouts. Moreover, those who may be experiencing supply difficulties.”Prof Jonathan Van-Tam, UK’s Deputy Chief Medical Officer
The Com-COV Study
This study has used two brands of vaccines. These are the AstraZeneca ChadOx1 nCoV-19) and Pfizer BioNTech BNT162b2.
Vaccine A – AstraZeneca ChadOx1 nCoV-19
The AstraZeneca vaccine contains a weakened adenovirus, which is a common cold virus, that came from chimpanzees. This genetically-changed weakened virus poses no harm to the human recipient. In addition, the AstraZeneca has genes that make proteins from the COVID-19 virus called Spike glycoprotein (S).
Once you receive the AstraZeneca vaccine, your body will develop an immune response to the Spike protein. In this way, the antibodies will keep the COVID-19 virus from entering the human cells and spreading the infection.
Vaccine B – Pfizer BioNTech BNT162b2
Unlike in AstraZeneca, Pfizer vaccines contains a packaged genetic coding material (mRNA) of the SARS-CoV-2 spike (S) protein. This S protein is within a very small fatty particles (lipid nanoparticles). As a result, the immune system will recognize these spike proteins and makes protection against them.
Contrary to the common misconceptions, the mRNA will be in fragments after. Therefore, it will be impossible to alter your genetic code.
There are 820 volunteer adult participants (aged 50 and above) from the Phase 1 of the ComCov study. The combinations have actually resulted a good immune response. They found that having the first dose of AstraZeneca followed by Pfizer has resulted to having higher antibodies and T cell responses compared to having Pfizer followed by AstraZeneca. . In terms of having the highest T cell response, it was seen from the AstraZeneca and Pfizer’s mixing of COVID vaccine schedule, respectively.On the other hand, they also saw that the mixing of COVID vaccines has produced higher antibodies than just having two doses of AstraZeneca.
The ComCov study led by Prof. Matthew Snape asserts that mixing of COVID vaccines are actually effective.
“We already know that both standard schedules are very effective against severe disease and hospitalizations, including against the Delta variant, especially in the span of eight to 12 weeks apart.”Prof. Matthew Snape, Lead investigator of Oxford ComCov Study
Other Studies on Mixing of COVID Vaccines
Similar with the ComCov study, there are other studies that proved the efficacy of mixing of COVID vaccines. For example, there is the CombiVacs trial from Spain. It has found that mixing of COVID vaccines such as the AstraZeneca and Pfizer posed a strong immune response. Interestingly, the mixing of COVID vaccines has produced SARS-CoV-2-specific immune cells (T celles) 4 times higher than one dose of AstraZeneca. Likewise, mixing of COVID vaccines has resulted to having 37 times greater production of SARS-CoV-2 neutralizing antibodies.
The WHO’s Stand on Mixing COVID Vaccines
With over 1.4 Million COVID deaths, it is very significant to have effective vaccines that will add more protection. Also, this will be beneficial for those who have underlying conditions, who are on a greater risk, as well as those who have recuperated from long-COVID. Long-COVID refers to people who still have COVID symptoms despite being recovered.
Despite the given European studies on mixing of COVID vaccines, the World Health Organization (WHO) warns its impact on health.
“It’s a little bit of a dangerous trend here. “It will be a chaotic situation in countries. Citizens will start deciding when and who will be taking a second, a third and a fourth dose.”Soumya Swaminathan, WHO Chief Scientist
Moreover, Swaminathan argues that there is a still a need for safety evaluation regarding the mixing of COVID vaccines.
The Countries Allowing the Mixing of COVID Vaccines
Despite WHO’s warning, there are countries, particularly in Southeast Asia, that are already conducting the mixing of COVID vaccines. These countries are Canada, Italy, Thailand, UAE, Bahrain, Bhutan, and Indonesia.
All these countries have resulted to mixing of COVID vaccines due to the lack of efficacy in terms of their protection against the new variants.
In Southeast Asia, Thailand is the first country to utilize mixing of COVID vaccines. According to their Head of the Centre of Excellence in Clinical Virology at Chukalongkorn University, Yong Poovorawan, the mixing of COVID vaccines will greatly help increase the herd immunity in a shorter time. In Thailand, the vaccine mix is from the Chinese-made COVID Vaccine Sinovac and Oxford-made AstraZeneca.
The Philippines’ Stand on Mixing of COVID Vaccines
In the Philippines, the Department of Science and Technology (DOST) will investigate and support the study on the efficacy of mixing of COVID vaccines. Dr. Michelle De Vera of the Philippine Society for Allergy, Asthma, and Immunology (PSAAI) will lead the study. Likewise, DOST will fund the study.
The study titled “𝐀 𝐬𝐭𝐮𝐝𝐲 𝐞𝐯𝐚𝐥𝐮𝐚𝐭𝐢𝐧𝐠 𝐭𝐡𝐞 𝐬𝐚𝐟𝐞𝐭𝐲 𝐚𝐧𝐝 𝐢𝐦𝐦𝐮𝐧𝐨𝐠𝐞𝐧𝐢𝐜𝐢𝐭𝐲 𝐨𝐟 𝐦𝐢𝐱𝐢𝐧𝐠 𝐝𝐢𝐟𝐟𝐞𝐫𝐞𝐧𝐭 𝐂𝐎𝐕𝐈𝐃-𝟏𝟗 𝐯𝐚𝐜𝐜𝐢𝐧𝐞𝐬 𝐚𝐧𝐝 𝐯𝐚𝐜𝐜𝐢𝐧𝐞 𝐩𝐥𝐚𝐭𝐟𝐨𝐫𝐦𝐬 𝐢𝐧 𝐅𝐢𝐥𝐢𝐩𝐢𝐧𝐨 𝐚𝐝𝐮𝐥𝐭𝐬” will run from June 2021 up to November 2022.
The Rationale of the Study
The mixing of COVID vaccine study will bridge the gap between the unpredictable vaccine supply to the pressing need to achieve herd immunity.
In addition, the participants of the study will be those people who have received Sinovac as the first dose because this is the most stable vaccine supply in the country thus far. Hence, the study will examine the efficacy of mixing of COVID vaccines such as that of Sinovac with the other vaccine brand.
In terms of locale, the study sample will be generated from the cities of Antipolo or Marikina, Manila, Pasig, Makati or Pasay, Muntinlupa, Quezon City, Cebu and Davao.
Indeed, the results of this study will give pertinent evidence on the safety of mixing of COVID vaccines. Consequently, this will be the basis of the policies, especially on which vaccines can be mixed as authorized by the Department of Health (DOH) for an Emergency Use Authorization (EUA).
Camella Manors: Your Safe Space
As we begin to approach the end of the year, we should continuously look forward to achieving a herd immunity so we can eventually experience a mask free Christmas. However, this will only be achieved if we all get inoculated. Hence, get vaccinated today and let us make your home at Camella Manors a safer space for you and your family.