BIRMINGHAM, Ala. (WIAT) — A doctor at the University of Alabama at Birmingham believes the United States could reach herd immunity in the fight against COVID-19 in late spring or early summer.

Dr. Suzanne Judd, a UAB epidemiologist, said there were a lot of factors to be considered. She remains cautiously optimistic about the decrease in case numbers and hospitalizations.

“The more people that have immunity the less the virus will spread, the safer it will be for us to interact with one another again,” said Judd.

In addition to the various COVID-19 vaccines being distributed across the state, Judd also pointed to results from a recent study by Columbia University that suggest more than one in three people has been exposed to the virus to develop natural antibodies.

Judd shared some of the numbers from Alabama.

“I think we have seen about 500,000 total positive tests, so you’re looking at maybe 1.5 million somewhere in that range, that possibly already have antibodies to SARS COV2 even though they have never tested positive for the virus. Some of them may not have even ever had symptoms,” said Judd.

Scientists believe 72% of the population needs to be exposed or vaccinated to achieve herd immunity.

Based on those expectations and the population in Alabama, Judd estimated herd immunity would require around 3.5 million residents to be exposed or vaccinated.

“Current estimates are that we will see it sometime late spring, early Summer in Alabama. Somewhere between May and June is likely, but this depends on many factors,” said Judd.

One potential factor, Judd said, would be some of the new and more contagious COVID variants. Doctors are currently studying the mutations, much like doctors do with various strains of the flu each year.

“There are some mutations that will be completely covered by the immune response the body has already developed,” said Judd. “There are other mutations that could escape the immune system and require a vaccine booster or actually lead to reinfection, so the variants are something we will have to watch very carefully.”

It is still too early for neighbors to let their guards down. Judd said it remains unclear if any of the vaccines actually stop transmission of the virus to others.

Doctors will continue to study health data to determine when and if it is safe to ease certain restrictions on gatherings.

“There is no magical, all of a sudden we are at 72% and we are safe. The things we are going to continue to monitor are the number of cases per week, we’re going to watch that very carefully, and as long as that trends down and stays below about 10 or five per 100,000 and we have decent testing in the state, then we will know it is safe to get people back together,” said Judd.

While the models offer hope, Judd and the Alabama Department of Public Health said preventative measures like masks, social distancing, and frequent handwashing will still be important in keeping numbers low.

“We do not have an absolute number when it comes to percent of persons that we believe to be vaccinated in order to really ensure that we have the level of immunity that we need,” said Dr. Karen Landers with ADPH.

Landers said it remains unclear how long immunity lasts and still recommends that neighbors receive the vaccine even if there was a past infection.

“We will have to continue to follow all of our other indicators, in terms of number of cases, persons that are hospitalized and other related information before we can come to conclusions,” Landers said.

Doctors like Judd believe there will likely be isolated COVID outbreaks, similar to flu outbreaks, but does see light at the end of the tunnel.

“I think that there are early indications that people are relaxing their behavior and cases are still not going up, so while I do watch the trends and I am always waiting for the other shoe to drop, they still look positive, even in light of the fact that people may be getting a little more comfortable being around other people,” said Judd.

Immunity needs to be studied in all corners of the state, including rural communities where vaccine access may have been limited or some are hesitant to take the dose.

“We need to make sure that we have a broad understanding of immunity across the state and a variety of communities,” said Judd.

For more information on herd immunity from UAB, click here.