As the world struggles to scale-up COVID-19 vaccinations, the emergence of new virus strains has left many countries wondering what these variants mean for pandemic response efforts—both now and in the future.

What are the COVID-19 variants? All viruses mutate over time, adapting to their environment and improving their survival. These new strains are called variants.

In May 2021, the World Health Organization (WHO) introduced a new naming system for COVID-19 variants using letters of the Greek alphabet. The Alpha variant, for example, was first detected in the United Kingdom, Beta in South Africa, Gamma in Brazil, and Delta in India. The system simplifies public reporting of the strains and minimizes the discriminatory practice of naming variants after the places where they are detected.

The WHO classifies variants as variants of interest and variants of concern in order to prioritize global monitoring and research.

Variants of interest have shown genetic changes that affect virus characteristics (e.g., transmissibility and disease severity) and may reduce the immune system’s ability to prevent infection. Variants of interest include Eta, Iota, Kappa, Lambda, and Mu.

Variants of concern have shown increased transmissibility, are more likely to evade detection, and are less responsive to vaccines and therapeutics. They may also lead to increased disease severity and are considered more dangerous. These include Alpha, Beta, Gamma, and Delta.

Over the past few months, the Delta variant has become the fastest-spreading variant in the world. It first appeared in late 2020 and led to the dramatic increase in COVID-19 cases across India and the United Kingdom. As of August 2021, Delta has been detected in around 130 countries and is currently driving an exponential surge in cases across the United States, Europe, and Asia and the Pacific.

Evidence shows that the Delta variant is not only more transmissible, it also leads to more hospitalizations and death—particularly among the unvaccinated. While data is still emerging, vaccines (especially Pfizer/BioNTech, Moderna, and AstraZeneca) have demonstrated protection against serious illness and death caused by Delta after two doses, with transmission among vaccinated individuals—so-called breakthrough cases—tending to be less severe illness and requiring significantly fewer hospitalizations.

No one is really safe until everyone is safe.

While global vaccination scales up across the globe, many low- and middle- income countries face a severe scarcity of vaccines. This uneven reality is made further apparent as wealthy countries are announcing plans to offer booster shots—third shots to people who have already received two doses. The global health community has cautioned against this, however, warning that it will only lead to greater vaccine inequity and may allow even more dangerous variants to take hold. Lambda, for example, another highly infectious variant first identified in Peru and rapidly spreading through South America, has shown vaccine resistance in studies.

For countries with limited vaccinations, COVID-19 is becoming a pandemic of the unvaccinated. Delta presents the greatest risk to these countries, particularly those with poorly equipped health facilities. In countries where vaccination rates remain low but variants of concern have taken hold, governments may have to resort to a cycle of mobility restrictions to contain and control outbreaks. 

In countries where vaccination rates are moderate, transmission may be blunted. But where disparities in vaccination rates exist and some communities are less vaccinated than others, localized outbreaks may occur (e.g., northeast US versus southern US). In countries where vaccination is high, herd immunity may be reached.

Although reintroduction of the virus could always be possible due to global mobility. 

To encourage vaccinations and help curb the Delta variant, some countries, like France and Italy, have instituted health passes that show proof of vaccination, a negative COVID-19 test, or COVID-19 antibodies in order to enter restaurants or bars (France) or for all workers (Italy). Although these requirements have sparked protests, they have also led to rises in vaccination rates.

Faced with the current reality, the best course of action to end this pandemic will be for countries to apply the good practices and lessons learned from the last year and half. These include:

1. Knowing their pandemic. This includes a focus on testing and understanding where infections are spreading (e.g., in urban vs rural areas).
2. Securing vaccines. Despite their limited availability, vaccines remain the single best protection against COVID-19.
3. Encouraging infection prevention and control measures like masking, social distancing, and avoiding large crowds.
4. Fortifying healthcare infrastructure and strengthening health systems in several areas that have proven critical during the current pandemic. This includes a focus on:
   • Strengthening surveillance to improve tracing of epidemiological events and data collection on variants;
   • Streamlining regulatory pathways for more efficient introduction of new vaccines;
   • Preparing vaccine service delivery systems for rapid deployment while also ensuring these efforts don’t undermine routine immunization services;
   • Developing robust and targeted risk communication to address vaccine hesitancy and misinformation before reluctance takes hold;
   • Building vaccine manufacturing capacity (where possible) so that local production can be ramped up during global supply shortages

COVID-19 continues to hold the world in its grip, as existing and emerging variants continue to circulate around the world. And with many global scientists predicting that the virus will become endemic—meaning it will likely continue to circulate for years ahead as a manageable threat—it is a reminder that both our present and future remain uncertain. 

Wealthy countries with high rates of immunization should not be lulled into a false sense of security—vaccinating their populations and offering boosters while less resourced countries have inadequate supply of vaccines. If they do, new variants will emerge from less vaccinated countries and spread to wealthy countries, threatening a return to normal life for everyone.

With this in mind, perhaps the greatest lesson of all is that no one is really safe until everyone is safe.