What is Pharmacovigilance?
Medicines and vaccines have transformed the prevention and treatment of diseases. In addition to their benefits, medicinal products may also have side effects, some of which may be undesirable and / or unexpected. Pharmacovigilance is the science and activities relating to the detection, assessment, understanding and prevention of adverse effects or any other medicine/vaccine related problem.
All medicines and vaccines undergo rigorous testing for safety and efficacy through clinical trials before they are authorized for use. However, the clinical trial process involves studying these products in a relatively small number of selected individuals for a short period of time. Certain side effects may only emerge once these products have been used by a heterogenous population, including people with other concurrent diseases, and over a long period of time.
WHO PIDM Members Meet in Costa Rica to Strengthen Pharmacovigilance Communication
The 44th Annual Meeting of the Members of the WHO Programme for International Drug Monitoring (PIDM) was held in San José, Costa Rica, from 25 to 27 September 2026 under the theme “Communication as an essential tool in pharmacovigilance.” The meeting brought together more than 145 pharmacovigilance professionals from 67 countries across all six WHO regions, with 105 participants attending in person and more than 40 joining virtually. The meeting provided a forum for representatives of national pharmacovigilance centres, national regulatory authorities and national immunization programmes to share their countries’ experiences and discuss practical approaches to strengthening risk communication, addressing misinformation and disinformation, leveraging artificial intelligence in pharmacovigilance, and advancing implementation of ‘The global smart pharmacovigilance strategy’. The meeting reinforced the importance of communication as a core component of pharmacovigilance and highlighted the value of global collaboration in promoting the safe use of medicines and vaccines worldwide. During the breakout group discussions, participants reflected on experiences, exchanged ideas and worked together to generate practical recommendations to WHO and to Member States. . These recommendations will be further consolidated and published in edition three of the WHO Pharmaceuticals Newsletter 2026.
WHO PIDM 2026 Meeting
79th World Health Assembly adopts resolution to strengthen pharmacovigilance
The Seventy-ninth World Health Assembly adopted a resolution to advance smart and efficient pharmacovigilance as a core element of strong and resilient health systems, marking a significant step towards expanding access to safe and effective medicines and vaccines worldwide and advancing progress towards universal health coverage.
The resolution calls on Member States to strengthen and integrate systems for monitoring the safety of medicines, vaccines and other health technologies, while improving regulatory capacity and workforce development. It also encourages the use of digital tools and real world data to enhance safety surveillance.
Emphasizing lessons from recent health emergencies, the resolution highlights the importance of timely detection of safety signals, effective risk communication and efforts to counter disinformation and misinformation.
Seventy-ninth World Health Assembly – Daily update: 22 May 2026
Vaccines, thimerosal and autism spectrum disorder
The Global Advisory Committee on Vaccine Safety (GACVS) reviewed the evidence regarding a potential link between vaccines and autism multiple times between 2002 and 2012, consistently concluding that the evidence does not support a causal relationship. To provide an updated and comprehensive overview of the published scientific literature on this topic, the WHO commissioned a review of studies from 2010 to 2025. The review finds that the most methodologically rigorous primary studies do not support a causal association between vaccines, including thiomersal-containing vaccines, and ASD.
Final report
This systematic review provides a current assessment of peer-reviewed studies published between 2010 and August 2025 investigating potential associations...
News
Publications
All →Estimation of background rates of adverse events of special interest in neonatal outcomes: preterm births,...
During pregnancy, women and infants are predisposed to specific infections due to various immunological and physiological changes. These infections can...
The global smart pharmacovigilance strategy
Trust in regulated medical products (medicines, vaccines and other health products) to protect health, is mostly based on a number of principles: the...
WHO pharmaceuticals newsletter - No. 2, 2025
The WHO pharmaceuticals newsletter provides you with the latest information on the safety of medicinal products and regulatory actions taken by authorities...
Protocol on estimation of thrombocytopenia background rates in children aged 5 months to <15 years in...
This is a master protocol approved by the WHO Research Ethics Review Committee on 20 May 2025. The protocol will be used by study sites that will submit...
Protocol on estimation of Guillain-Barré syndrome background rates in general population in low- and...
Background rates of possible adverse events are crucial to monitoring vaccine safety as they help separate potential safety signals following vaccination...
WHO pharmaceuticals newsletter - No. 1, 2025
The WHO pharmaceuticals newsletter provides you with the latest information on the safety of medicinal products and regulatory actions taken by authorities...
On the front page also: Protocol identifying number: ERC.0004184. Use of this protocol: As a master protocol to be approved by WHO Ethical Review Committee...
Landscape analysis of pregnancy exposure registries in low- and middle-income countries
Many vaccines and drugs hold the promise of reducing mortality and morbidity among pregnant women and infants living in low- and middle-income countries...
Guidance for clinical case management of thrombosis with thrombocytopenia syndrome (TTS) following...
Thrombotic Thrombocytopenia Syndrome (TTS) has emerged as a new adverse event following immunization in individuals vaccinated with COVID-19 non-replicant...
About us
The WHO Pharmacovigilance team strives to ensure safer use of medicines and vaccines throughout the life cycle of the products. We produce reliable, balanced information on the benefits and risks of medicines and vaccines, which enhances people’s care and safety.
Team Lead: Dr Shanthi Pal
Among our activities we are:
- Developing norms, standards and guidelines.
- Providing credible safety and regulatory information on medicines.
- Appointing and convening global advisory committees of experts to review and provide guidance on the safety of medicines and vaccines.
- Hosting global networks such as the WHO Programme for International Drug Monitoring (PIDM) to promote pharmacovigilance in countries.
- Establishing and maintaining WHO Collaborating centres (WHO CCs) to provide technical support to countries in pharmacovigilance.
- Countering vaccine-misinformation about vaccines through the Vaccine Safety Net (VSN), which facilitates the access to reliable information on vaccine safety.
- Providing training programmes to build and strengthen the capacity of national safety surveillance systems for medicines and vaccines .
- Developing innovative methods and tools to generate new evidence on the safety of medicinal products