A federal advisory panel wants all U.S. adults to get vaccinated against whooping cough. 

The panel voted Wednesday to expand its recommendation to include all those 65 and older who haven't gotten a whooping cough shot as an adult.

Children have been vaccinated against whooping cough since the 1940s, but a vaccine for adolescents and adults was not licensed until 2005. Since then, the Advisory Committee on Immunization Practices has gradually added groups of adults to its recommendations, including 2010 advice that it be given to elderly people who spend a lot of time around infants.

Wednesday's recommendation means now all adults should get at least one dose.

"They've been moving up to this in baby steps," said Dr. William Schaffner, a Vanderbilt University vaccines expert.   

Whooping cough facts in Canada:

  • Also called pertussis, it's a highly contagious respiratory tract infection that can turn into severe coughing (a "whooping" sound), choking and vomiting. Can last for weeks or months, and can cause brain damage or even death. Most dangerous when when baby is under six months old.
  • Symptoms are similar to the common cold, including runny nose, red watery eyes, mild fever and cough.
  • Spread through coughing and sneezing. The infection also spreads when children touch toys or other things that someone with pertussis has handled and then rub their eyes or mouths.
  • About one of every 400 babies hospitalized for pertussis will die of either pneumonia or brain damage.
  • In Canada in 2005 and 2006, there were 2,500 cases reported each year. 
  • The pertussis vaccine is given by needle and is safe for most people. It is part of a combined vaccine, called the 5-in-1 vaccine, that protects children from five serious diseases at the same time: diptheria, polio, pertussis, tetanus and Haemophilus influenzae type b to protect against meningitis. There may be mild side-effects such as slight fever, and make children fussier, sleepier or have less appetite than usual.
  • A child who has had a severe allergic reaction to a previous dose of the pertussis vaccine should not get the vaccine again.

Source: Public Health Agency of Canada

Whooping cough, or pertussis, is a highly contagious bacterial disease that in rare cases can be fatal. It leads to severe coughing that causes children to make a distinctive whooping sound as they gasp for breath. Recommendations from the panel are usually adopted by the government, which sends the guidance out to doctors.   

Contributing to the push to vaccinate more adults was a California whooping cough epidemic in 2010 that infected 9,000. Ten babies died after exposure to infected adults or older children.

There's little data on how many elderly people have gotten the vaccine. Only about eight per cent of adults under 65 have been vaccinated, compared to about 70 per cent of adolescents.

Health officials believe whooping cough is underreported in older adults, perhaps because in older people the illness can be hard to distinguish from other coughing ailments.

Series of shots recommended

A goal of the recommendation is to prevent teens and adults from spreading the disease to infants, although there's no good evidence this "herd immunity" approach has worked so far. Vaccination for children is included in a series of shots, beginning at two months.

The adult vaccine combines protection against tetanus, diphtheria and whooping cough. One version of the vaccine, made by GlaxoSmithKline, was licensed for use in the elderly last year. The committee said another version, made by Sanofi Pasteur, can also be given. Both cost about $35 US a dose.

The shot is as safe as a regular tetanus booster. Estimates range widely for how effective the vaccine is at preventing whooping cough in older adults, or how much its protection wanes years afterward. 

In Canada, officials in various provinces have urged vaccination against whooping cough in recent months.

In New Brunswick, infection was confirmed at two schools in the province last month, and the regional medical officer of health for the Moncton area warned the province was overdue for an outbreak.

As well, B.C.'s Fraser Health Authority has been stockpiling whooping cough vaccine, preparing for a possible outbreak, after more than 100 cases of whooping cough were noted in Chilliwack, Agassiz, and Hope. However, while the health authority was pushing to get more adults immunized, the BC Centre for Disease Control said widespread adult immunization wasn't necessary.

According to the Public Health Agency of Canada, Canadian guidelines recommend that all children get four doses of a combined vaccine that includes pertussis protection – at ages two months, four months, six months and 18 months — and a booster vaccine at four to six years of age. An additional booster dose, combined with tetanus and diphtheria (Tdap) vaccine, is given routinely to adolescents between 14 to 16 years of age.

The federal agency also says there are about 2,500 cases of whooping cough per year in the country, and one to three deaths occur, particularly in infants too young to have begun their immunization and in infants who have not been fully immunized. The federal agency says the number of adolescents and adults getting whooping cough has steadily increased, making protection of adolescents and adults "a worthy goal."

With files from CBC News