Heterologous COVID-19 vaccinations of Covishield/Astrazenica and Pfizer/Biontech: a case report

Tamer M. Kolaib, Rehab M. Sabry


The most significant scientific breakthrough in the fight against COVID-19 pandemic is the speedy creation of COVID-19 vaccinations. Despite the fact that all licensed vaccines' efficacy and safety have been shown in large clinical trials, but the data regarding heterologous vaccination regimens' efficiency and safety is still limited. Heterologous schedules are intriguing for a variety of reasons, including logistical and therapeutic efficacy. The approval of heterologous vaccination will give countries with limited vaccine access and countries where different vaccines may become available at different times the opportunity to make vaccination programmes more flexible in response to supply fluctuations. Heterologous regimens have the potential to elicit a greater response, resulting in increased efficacy. In this case report we presented an adult male who was inadvertently given a combination of Covishield and Pfizer COVID-19 vaccines within a 3 weeks interval period. This event happened accidentally. The patient was reassured and followed up after 8 weeks without any adverse reaction.



COVID-19, Vaccination, Heterologous

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WHO. Coronavirus (COVID-19) Dashboard, 2019. Available at: Accessed on 20 August 2021.

Liu X, Shaw RH, Stuart ASV, Greenland M, Aley PK, Andrews NJ, et al. Safety and immunogenicity of heterologous versus homologous prime-boost schedules with an adenoviral vectored and mRNA COVID-19 vaccine (Com-COV): a single-blind, randomised, non-inferiority trial. Lancet. 2021;398(10303):856-69.

Raddad LJ, Chemaitelly H, Ayoub HH, Yassine H M, Benslimane F, Khatib HA, et al. Protection afforded by the BNT162b2 and mRNA-1273 COVID-19 vaccines in fully vaccinated cohorts with and without prior infection. medRxiv. 2021.

Anand P, Stahel VP. Review the safety of Covid-19 mRNA vaccines: a review. Patient Saf Surg. 2021;15(1):20.

Salles T, Alhambra D. Heterologous vaccine regimens against COVID-19. Lancet. 2021;398(10295):94-5.

Spencer AJ, McKay PF, Rammerstorfer S, Ulaszewska M, Bissett CD, Hu K, et al. Heterologous vaccination regimens with self-amplifying RNA and adenoviral COVID vaccines induce robust immune responses in mice. Nat Commun. 2021;12(1):2893.

Kumar VM, Perumal SR, Trakht I, Thyagarajan SP. Strategy for COVID-19 vaccination in India: the country with the second highest population and number of cases. NPJ Vaccines. 2021;6(1):60.

Kunal S, Sakthivel P, Gupta N, Ish P. Mix and match COVID-19 vaccines: potential benefit and perspective from India. Postgrad Med J. 2021;140648.

Shaw RH, Stuart A, Greenland M, Liu X, Nguyen Tam JS, et al. Heterologous prime-boost COVID-19 vaccination: initial reactogenicity data. Lancet. 2021;397(10289):2043-6.