The whooping cough vaccine may be dwindling in effectiveness because the bacteria has mutated, the Centers for Disease Control and Prevention (CDC) warns.
Researchers looked at laboratory samples of patients who had the infection between 2000 and 2013.
They found that the bacteria that causes the disease, Bordetella pertussis, underwent genetic changes in the last decade.
This means that the current available vaccine matches an ‘older version’ of the disease, reported NBC News.
While the team insists the vaccine is still the best protection against the condition, they hope the findings, published in the journal Emerging Infectious Diseases, will help researchers develop a better, more effective vaccine.
Researchers from the CDC say the bacteria that causes whooping cough, Bordetella pertussis, underwent genetic changes in the last decade (file image)
Usually, whooping cough is reported in singular cases. However, several states, have reported school-wide outbreaks this year.
The Los Angeles Times reported that 30 students at the prestigious Harvard-Westlake School fell ill with whooping cough, part of a larger outbreak of 50 cases in the LA-area.
And, just 100 miles south, officials in San Diego County have confirmed at least 70 cases of pertussis, according to KGTV.
Meanwhile, at least 36 cases have been confirmed, mostly among young children, in school districts in South Dakota.
Whooping cough, also known as pertussis, is a respiratory tract infection that is highly contagious.
When someone coughs, sneezes or talks, infected droplets are sprayed into the air, where other people can inhale them and are then infected.
In serious cases, sufferers experience bouts of coughing that end with a ‘whoop’ sound when a breath is taken.
The first symptoms usually resemble those of a cold or flu including coughing, runny nose and a fever.
However, after one to two weeks, sufferers experience severe coughing fits due to mucus blocking the airways, which can last up to 100 days.
The best protection against whooping cough comes from the DTaP vaccine, which also protects against diphtheria and tetanus.
It is given as a series at two months, four months, six months, 15 to 18 months, and then four to six years.
The CDC recommends children between ages 11 and 12 receive a booster with a similar vaccine called Tdap.
Prior to the vaccine’s introduction in the 1940s, about 200,000 children contracted whooping cough every year with about 90,000 dying.
According to the CDC’s latest figures, nearly 13,500 cases were reported in 2018 with about 10 deaths.
But, even after a child receives all five doses, the DTaP and Tdap vaccines are between 80 and 90 percent effective, lower than the rates for other vaccine-preventable diseases.
This is why the concept of ‘herd immunity’ is so important when it comes to preventing the spread of whooping cough.
‘Herd immunity’ occurs when the vast majority of a community – between 80 and 95 percent – becomes immune so that, if a disease is introduced, it is unable to spread.
Therefore, those who are unable to be vaccinated, including the ill, very young and very old, are protected.
‘The pertussis vaccine is not optimal,’ Dr. William Schaffner, a professor of preventive medicine at Vanderbilt University Medical Center in Nashville, Tennessee, told NBC News.
‘We’re making the best use of the vaccine, while we’re frantically doing research to make a better one.’
The new report comes as the US battles an outbreak of another highly contagious childhood disease: measles. Since the start of 2019, the CDC has confirmed 228 cases in 12 states.
Federal health officials say the spread of misinformation online about vaccines are to blame for the outbreaks.