Pharmacovigilance is the science and activities relating to the detection, assessment, understanding and prevention of adverse effects or any other medicine-related problem. Although all medicines are required to undergo rigorous testing for safety and efficacy through clinical trials before they receive a marketing authorisation (license), the full extent of their potential adverse effects cannot be known at that point. The clinical trials process generally involves a relatively small number of selected participants, studied over a relatively short period of time. Some rarer adverse drug reactions (ADRs, sometimes referred to as ‘side-effects’) may only emerge after medicines are used more widely among tens of thousands of people, who are less carefully selected and monitored, have other diseases, take potentially interacting drugs, and are exposed to the new medicine over a longer period of time.
The COVID-19 pandemic has forced us all to confront these issues head on. The impact of infection has put significant pressures on health-care services by causing illness, hospitalisation and deaths. Nearly 140,000 people across the UK have died within 28 days of a positive test for COVID-19. Part of the response has been a major effort to develop and deploy effective Covid-19 vaccines around the world. Here in the UK, a national immunisation campaign has been underway since early December 2020. Three COVID-19 vaccines (Pfizer/BioNTech, Oxford/AstraZeneca and Moderna) are currently being used in the UK. All have been approved by the Medicines and Healthcare products Regulatory Agency (MHRA) following a thorough review of safety, quality and efficacy information from clinical trials. However, this was done under emergency or temporary authorisation, after a much shorter than usual development and clinical programme.
In those clinical trials, the vaccines showed very high levels of protection against symptomatic infections with COVID-19. Subsequent ‘real world’ data has confirmed the efficacy of the vaccines in preventing serious illness and hospitalisation. But what of safety?
Following emergency approval it was recognised that an intensive pharmacovigilance process would be necessary. The pre-authorisation clinical trials in around 50,000 volunteers had demonstrated that some predictable vaccine side-effects were very common (injection site pain, fatigue, headache, muscle pains, chills, joint pains, and fever). The key question was, would anything else emerge?
Healthcare professionals and the public were urged to report adverse events suspected to be related to vaccination through a dedicated reporting portal. To date around 40 million Pfizer and 50 million AstraZeneca vaccine doses have been administered. As of 22 September 2021, 117,297 Yellow Card reports have been reported for the Pfizer/BioNTech vaccine and 233,242 have been reported for the COVID-19 Vaccine AstraZeneca. These data, including the nature of the adverse event, number of reports made and number of deaths have been continuously available and regularly updated on a dedicated MHRA website, openly available to scrutiny by all.
The data have been widely cited, debated and also misused. However, these discussions have provided us with the opportunity to disseminate some very important messages relevant to pharmacovigilance:
- The safety profile of any new medicine (not just those approved under emergency authorisations) is never fully known at the point it is launched onto the market
- Although the scientists and manufacturers have primary responsibility for the safety of medicinal products, everyone (including members of the public) has a role to play in that process by reporting suspected ADRs
- It can be hard to distinguish adverse events occurring in association with medical treatment from spontaneous events that happen frequently in the population; a causal association only becomes clearer as more Yellow Cards reports are made (‘signal generation’)
Even the profile of the MHRA as a body has been greatly increased, even if the comments have not always been supportive. Although the nearly 100 million vaccine doses is impressive it is worth remembering that there are around a billion prescriptions issued every year in the UK for thousands of other medicines. These collectively result in just around 30,000 reports annually. The pandemic now offers a golden opportunity for those of us involved in the process of pharmacovigilance to harness the awareness of and enthusiasm for reporting suspected ADRs in the coming years. The value of the Yellow Card scheme reporting has been demonstrated on many occasions and has led to regulatory changes that enhance safety for patients.
If you read this blog and are inspired to contribute to the pharmacovigilance process, consider reporting any suspected adverse drug reactions at https://yellowcard.mhra.gov.uk.
– Professor Simon Maxwell, Medical Director YCC Scotland, October 2021
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