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'Typhoid Mary' still stalks the world, but scientists show older vaccine works against the old foe

Meredith Cohn, The Baltimore Sun on

Published in Health & Fitness

The group compared results from another 14,000 children in Malawi who didn’t get the typhoid vaccine. They were given a vaccine for meningitis so they would still get an immediate benefit from participating in the trial.

Neuzil said there has long been another typhoid vaccine approved for use, but it’s expensive and mostly used by travelers from wealthier countries, including the United States, each time they visit an affected country because the immunity it offers isn’t long-lasting.

Also, that vaccine can’t be used for those under age 2, excluding a large at-risk group of kids. Children also are routinely vaccinated against a number of diseases at one time at a young age and likely wouldn’t return for an additional vaccine later.

The vaccine trial showed that protections from the old typhoid vaccine may last for years, maybe five or more.

Work on the vaccine began in 2001 in India by Barat Biotech International, but the vaccine was not mass-produced before now for economic reasons, Neuzil said. Basically, poor countries couldn’t afford it, while wealthier nations didn’t need it.

It was given what’s called prequalification by the World Health Organization in 2018 based on immune levels in recipients and good manufacturing procedures. There also have been limited other studies showing it works in different ages and geographic settings.

The large study from the field in Malawi could help secure buy-in from countries that have a lot of competing health concerns and may not have given typhoid priority at any age, Neuzil said.

Another international group, Gavi, an alliance funded with nonprofit and government money, agreed recently to pay for the vaccine and distribution for children as young as 9 months old during routine vaccination periods. The group also agreed to a one-time campaign to vaccinate older kids up to age 15.

 

Gavi also is working to distribute COVID-19 vaccine in low-income countries.

The vaccine study is promising, though the world still must live with typhoid for the foreseeable future, said Dr. Myron Levine, the Maryland medical school’s associate dean for global health, vaccinology and infectious diseases.

Levine, co-founder of the Center for Vaccine Development and its former longtime director, has worked on typhoid prevention for decades and said the Malawi study provided important evidence of the vaccine’s efficacy in an African country for the first time.

But even with widespread use of the vaccine — and improvements to water systems — typhoid is sneaky. The bacteria-caused disease isn’t passed on by animals but can be passed on by human carriers, sometimes known as a “Typhoid Mary.” Tracking every one of them is nearly impossible in densely populated countries like Bangladesh and Pakistan where it’s common.

However, it may be possible in a place like Samoa, Levine said. His work helped launch a vaccination and surveillance program in the tiny Pacific island years ago.

Still, he said, evidence of an effective long-lasting vaccine that can be used in small children comes at a good time, considering that only two antibiotics still seem to control the infections. Those treatments aren’t always easy to come by and also could stop working.

“We are a step away from typhoid being untreatable, so if we don’t prevent it, the fatality rate will really rise,” he said. “This vaccine, it’s really good news.”

©2021 The Baltimore Sun. Visit at baltimoresun.com. Distributed by Tribune Content Agency, LLC.