Researchers have identified a more dominant and contagious form of the coronavirus that’s going to be challenging to contain and treat.

Scientists at Los Alamos National Laboratory have identified the new strain that has dominated the world since mid-March, they say. In addition to spreading faster than the original version of the virus, it also makes people more vulnerable to a second infection.

According to the Los Angeles Times, this discovery may negatively impact scientists developing a COVID-19 vaccine since research has been based on the genetic sequence of earlier strains and may be ineffective against this one.

The Los Alamos team, assisted by researchers from Duke University and the University of Sheffield in England, identified 14 mutations of the current coronavirus. They expressed the most concern about the mutation called D614G, which is responsible for the virus’ change in spikes.

“When viruses with this mutation enter a population, they rapidly begin to take over the local epidemic, thus they are more transmissible,” study leader Bette Korber, a biologist at Los Alamos, wrote on her Facebook page.

According to The Hill, researchers have speculated that the virus mutates as it migrates around the globe, possibly mutating every 15 days.

Scientists at major organizations developing vaccines or drugs to combat the coronavirus, were hoping that it would not mutate like the influenza virus does. The Los Alamos research may dash those hopes, says the Times.

“D614G is increasing at an alarming rate, indicating a fitness advantage relative to the original Wuhan strain that enables more rapid speed,” the study authors wrote. However, the study did not indicate if the new strain is more lethal than the original. According to hospital records, hospitalization rates were about the same for people infected with either version of the virus.

But, according to the Times, another worry is that people who have become infected with the older version of the virus would not have immunity to the second strain. If this is the case, the authors wrote, it could make “individuals susceptible to a second infection.”