The colossal undertaking that is the global rollout of COVID-19 vaccines is facing another gargantuan challenge: monitoring their safety over time.

The vaccines have proven to be safe and effective in clinical trials. Yet as with the rollout of any new medicine or treatment, it takes time to see the bigger picture. Clinical trials, including those for the COVID-19 vaccines, follow thousands of volunteers from a limited population for several months. Now billions of people all over the world will be inoculated with them, with a lifetime of consequences. Even as policymakers and experts communicate the benefits of the vaccines to win over the hesitant, we must monitor for unwelcome side effects. If these adverse events are not documented and publicly addressed, they can further undermine public confidence in the vaccines, and scientific medicine more generally. And right now, there are big blind spots in our global ability to do this.

Many low- and middle-income countries don’t have the capacity to monitor and report adverse events as they occur

Many low- and middle-income countries, particularly in sub-Saharan Africa, don’t have the capacity to monitor and report adverse events as they occur. During the last major pandemic, of 2009 H1N1 influenza, few of these countries were able to adequately monitor side effects from the vaccine.

The conditions in which poor countries distribute vaccines may also contribute to more adverse events. Some countries, including Russia and India, approved vaccines for COVID-19 while clinical trials were still ongoing and before test results had been publicly reviewed. Resource-poor countries will face challenges with keeping vaccines cold enough and delivering them before they expire. They are also more likely to have substandard and falsified products. Careful tracking will measure how these variables impact safety.

The global health community is building the plane while flying it. In late December, the World Health Organization, a partner in the COVAX effort to provide equitable access to COVID-19 vaccines, released standardized guidance for how to collect, analyze and share safety data for COVID-19 vaccines. This stems from hard lessons gleaned from the H1N1 pandemic and the hasty introduction of the dengue vaccine in the Philippines, which turned out to actually worsen the disease in children not previously exposed to dengue. However, many countries lack the money, systems, and trained health workers to put this guidance into practice. They may also lack accurate and complete demographic data or civil registration records.

Establishing good safety surveillance systems will benefit all medicines, not just COVID-19-related products. The same processes, infrastructure, skills, and tools will be necessary to measure the safety of new medicines for drug-resistant tuberculosis, new combination treatments for HIV, and vaccines for dengue and Ebola, among others—many of which are being introduced in lower income countries first, without the benefit of the surveillance available in high-income countries.

An accurate, comprehensive safety monitoring program should be front and center in any vaccine rollout plan

Some countries are establishing these necessary systems. Many countries in Africa are transitioning to a more potent, long-lasting, and convenient HIV combination treatment. The organization we work for is supporting Mozambique and Rwanda to set up pharmacovigilance systems to monitor new treatments and vaccines. This involves helping their governments develop a protocol for monitoring a cohort of patients exposed to the medicines or vaccines, providing supportive supervision, and training health-care providers and regulators to collect and analyze data to inform local clinical and regulatory decisions.

We’ve also helped these countries and the Philippines introduce an electronic tool to capture and analyze data on medicine rollouts. Rwanda is using it to monitor outcomes from administration of the new Ebola vaccine, including watching for miscarriages and stillbirths among women who become pregnant after vaccination. And we are supporting the rollout of the COVID-19 vaccine in Ukraine and Jordan and building their monitoring infrastructures at the same time. New technology, including mobile-phone applications for real-time reporting of adverse events, is also helping community health workers in low- and middle-income countries report suspected COVID-19 cases.

These efforts will require a great deal of time, coordination, funding, and political will to start and sustain. Competing priorities, such as the purchase and distribution of vaccines themselves, might make these investments seem dispensable. But an accurate, comprehensive safety monitoring program should be front and center in any vaccine rollout plan, including for COVID-19. It takes a holistic strengthening of the people and processes involved in the entire pharmaceutical system to monitor COVID-19 remedies and for other lifesaving innovations going forward. Governments, drug makers, researchers, health workers, and consumers must collaborate and do their part to put it into practice.

As we scramble to get safe, effective vaccines to every country that needs them, let’s keep this goal in sight and establish sound, sustainable monitoring systems that will make future vaccine rollouts as dependable and efficient as possible.