The World Health Organization warned Thursday that the surging COVID-19 pandemic in many parts of the world increases the likelihood that new, potentially dangerous variants may emerge in the future.
"The pandemic is nowhere near finished," said Professor Didier Houssin, chair of the WHO Emergency COVID-19 Committee.
The global surge in new cases has highlighted the ongoing challenges posed by the pandemic. In Africa, cases surpassed their second wave peak during the seven days ending on July 4 and the death toll this week climbed by 40%, according to WHO.
At the start of the pandemic, there was only one variant of the SARS-CoV-2 virus. As the virus spread across the globe, it mutated, sprouting thousands of new versions of itself -- some of which were more contagious than the original.
Currently, there are four variants of concern, labeled by the WHO using the Greek alphabet. The most recent, the delta variant, which was first detected in India, has been identified in more than 111 countries and is now responsible for nearly 60% of all cases in the U.S.
"We expect it to be the dominant strain circulating worldwide, if it isn't already," said WHO Director-General Dr. Tedros Adhanom Ghebreyesus.
As the virus continues to spread, new variants might emerge in the future that may be even more challenging to control, the WHO warned.
Vaccines are one of the world's most important tools to prevent the spread of current SARS-CoV-2 variants, giving the virus less of an opportunity to evolve into new variants. But many countries don't have enough vaccine supply. Globally, only 25.8% of the world's population has received at least one dose of a COVID-19 vaccine, according to the University of Oxford's Global Change Data Lab.
The WHO continued to stress Thursday the importance of leveraging all vaccines currently approved for emergency use and issued a call to action to have at least 10% of every country's population vaccinated by September 2021.
The WHO encouraged wealthier countries to share vaccine supplies with the rest of the world. Combined with vaccinations, use of evidence-informed public health and social measures, including masks, physical distancing and hand hygiene, remains the most effective strategy for combatting the spread of all SARS-CoV2 variants.
"The virus continues to evolve, resulting in more transmissible variants," Ghebreyesus said last week, as the world marked four consecutive weeks of rising cases.
Chidimma J. Acholonu, M.D., M.P.H.. is a pediatric resident physician at the University of Chicago and a contributor to the ABC News Medical Unit.