Precautionary measures are at the heart of pharmacovigilance, where proactive safety actions can mean the difference between protection and peril. Regulatory agencies are not just passive observers – they actively monitor, assess, and intervene when necessary to safeguard public health.

For example, what happens when a vaccine designed to protect the vulnerable becomes a potential risk for the people it aims to safeguard?

This is not a theoretical question – it’s the real-life story of the IXCHIQ Chikungunya vaccine, and how global regulatory bodies responded swiftly with precautionary measures in pharmacovigilance to protect public health.

What Are Precautionary Measures?

Pharmacovigilance is more than collecting adverse event reports. It’s a continuous risk assessment, communication, and timely intervention process. At its core lies a set of actions known as precautionary measures – regulatory tools used when early safety signals raise concern, even before complete scientific certainty is reached.

These measures include:

• Temporary restrictions or suspensions of drug use.

• Communication of new safety information to the public and healthcare professionals.

• Updates to product labelling and risk management plans (RMPs).

• Post-authorisation safety studies (PASS).

• Targeted monitoring in high-risk populations.

These interventions aim to minimise harm before conclusive evidence is available – when a signal is strong enough to warrant caution.

Case Study of Precautionary Measures: Chikungunya Vaccine Dilemma

A recent example of these principles in action is the IXCHIQ vaccine, a live-attenuated vaccine against the Chikungunya virus.

When the IXCHIQ vaccine was granted EU approval in June 2024, it marked a milestone. For the first time, vulnerable populations in Chikungunya-endemic regions had access to a live-attenuated vaccine to prevent this mosquito-borne disease.

However, what appeared to be a public health triumph soon became a subject of intense scrutiny.

By May 2025, reports began to emerge from France of serious adverse reactions following vaccination – especially in individuals over 65 years of age. Many of these patients had pre-existing conditions, and the nature of the events ranged from severe systemic reactions to, tragically, two fatal outcomes.

EMA Responds: A Precautionary Recommendation

The European Medicines Agency’s Pharmacovigilance Risk Assessment Committee (PRAC) initiated a scientific review of the vaccine’s safety data, focusing on older people. At the time, 17 serious adverse events had been reported globally, all involving individuals aged 62–89.

PRAC noted that the clinical trials leading to IXCHIQ’s approval had primarily enrolled individuals under 65, leaving a significant data gap for older age groups. With the postmarketing data raising red flags, the agency did not wait for conclusive proof. Instead, it acted.

The precautionary measure? A temporary restriction on IXCHIQ use in people aged 65 and older.

This decision reflected a core principle in pharmacovigilance: better safe than sorry.

A Global Safety Conversation

EMA wasn’t alone in its concerns. Around the same time:

The U.S. Food and Drug Administration (FDA) and Centers for Disease Control and Prevention (CDC) began investigating postmarketing reports from the U.S., including six serious events among elderly recipients. The FDA and CDC issued guidance in the United States, recommending a pause in use for individuals aged 60 and older while investigations continued.

The Commission on Human Medicines (CHM) in the UK also recommended temporary restrictions, citing 23 global reports of serious adverse reactions, including two deaths.

Authorities in several countries highlighted that most serious cases occurred in patients with chronic underlying conditions, such as cardiovascular disease or immunosuppression.

Reassessment and a Balanced Conclusion

In July 2025, after further investigation, the EMA’s Committee for Medicinal Products for Human Use (CHMP) lifted the temporary restriction. However, it added a clear recommendation: the vaccine should only be used when the risk of Chikungunya infection is high and after careful individual benefit-risk evaluation.

In other words, use caution, and do not abandon it entirely.

This nuanced stance illustrates the strength of precautionary pharmacovigilance – not reactive bans, but data-driven, proportional action that evolves as evidence grows.

Why This Case Matters for Precautionary Measures in Pharmacovigilance

The IXCHIQ case highlights key lessons for pharmacovigilance. Postmarketing surveillance remains essential, as clinical trials can’t capture all risks – especially rare or age-specific ones. Older people, often with comorbidities and altered drug responses, require special consideration when trial data are lacking. 

The case also underscores the value of international coordination: agencies like EMA, FDA, CDC, MHRA, and CHM collaborated and shared information, enabling faster and safer decisions. Most importantly, it shows that precautionary measures are not overreactions but necessary steps to protect public health. These flexible and temporary actions allow time to gather more data and reassess risks without causing panic. 

IXCHIQ was not withdrawn but used more cautiously, demonstrating how early, proportionate interventions can manage uncertainty while maintaining public trust.

Conclusion

Precautionary measures in pharmacovigilance are not a sign of weakness. They are a sign of maturity.

The IXCHIQ story shows how pharmacovigilance is more than adverse event reports – it’s about making difficult decisions under uncertainty, guided by science, ethics, and patient safety.

For every regulatory professional, the message is clear: Stay alert. Intervene early. Protect lives.

Because when we act with precaution, we don’t just manage risk – we lead responsibly.