Vaccinating pregnant women against whooping cough is the best way to protect their newborns from respiratory infections that can prove fatal, according to new recommendations from the Global Pertussis Initiative (GPI).

If inoculation during pregnancy isn't feasible, the next best option is vaccinating immediate family members, caregivers and other people who regularly come in close contact with infants, according to the GPI, a group of scientists focused on eradicating whooping cough.

"Pertussis infection in small infants is particularly devastating," Dr. Kevin Forsyth, lead author of the guidelines, said in an email. In addition to intense, uncontrollable coughing fits caused by the lung disease, it can also lead to potentially fatal side effects like septic shock and suffocation, he said.

"The best thing parents can do is have the mother immunized during pregnancy, which boosts her immunity and transfers protection to the baby,” added Forsyth, who is a professor of pediatrics a Flinders University in Adelaide, Australia.

The bacteria Bordetella pertussis causes whooping cough, which gets its nickname from the sounds patients make as they gasp for air during intense coughing fits. Pertussis is highly contagious and easily spread when an infected individual coughs or sneezes.

Each year, an estimated 16 million people worldwide catch pertussis and about 200,000 of them die, according to the U.S. Centers for Disease Control and Prevention. About half of babies under age one who catch pertussis require hospitalization.

Health officials in many countries recommend vaccination during pregnancy, as well as a series of three shots for infants starting sometime between 6 weeks and 3 months of age. Some countries, including the U.S. and the U.K., also recommend that women get vaccinated during each pregnancy because effectiveness of the shot wanes over time, according to the GPI position statement in the journal Pediatrics.

Extending vaccination to all individuals who come in contact with infants, a practice known as cocooning, might be even more effective than only inoculating pregnant women. Siblings, grandparents, and caregivers, for example, would get vaccinated at least two weeks prior to coming in contact with the infant, Forsyth told Reuters Health.

"The theory is that if people in close contact with the infant are not carrying the germ, then they cannot transmit it to the infant," Forsyth said. "Yes, it works, but practically it is not really feasible."

Unlike some other vaccines, which can provide immunity for years, the shots for pertussis lose effectiveness fairly quickly, said Dr. Bonnie Maldonado, chief of the division of infectious diseases in the pediatrics department at Stanford University School of Medicine and a member of the American Academy of Pediatrics committee on infectious diseases.

"If you look at mothers' antibodies after vaccination they are pretty high for the first nine months, then within two years the antibody levels have dropped very low," said Maldonado, who wasn't involved in the study. "That's why the mother needs a dose for every pregnancy."

Vaccinating pregnant mothers may be up to 90 percent effective in preventing infants from getting pertussis, and the cocoon approach to inoculation may be about 60 percent to 70 percent effective, Maldonado told Reuters Health.

"Pertussis can affect anybody at any age, but the risk is highest for severe symptoms and complications for young babies because of their small airways," Maldonado said. "We need to make sure that infants at high risk are protected until their vaccinations are complete."

Forsyth has received funds from Sanofi Pasteur, a vaccine maker. His co-authors have received funds from Sanofi as well as from vaccine producers Merck & Co., GlaxoSmithKline and Novartis.