Polio is close to being eradicated worldwide, but the virus still circulates in Afghanistan and Pakistan, Tina Hesman Saey reported (SN: 9/14/19, p. 4) in an update to a 1969 story, “Polio could come back” (SN: 9/13/69, p. 206).
In African countries, one source of polio cases are vaccines
made with viral strains that rarely can become disease-causing, Saey
reported. Reader Mike Bushroe wondered why those vaccines are used.
“It’s a complicated issue,” says Oliver Rosenbauer,
spokesman for the Global Polio Eradication Initiative in Geneva. There are two
types of polio vaccines — oral vaccines and the inactivated vaccine, which is
given as a shot.
Oral vaccines contain weakened viral strains and offer two
benefits: They can spark a person’s immune system to make a memory of the virus
without the person getting sick, and the weakened strains can spread to people
close by, passively immunizing them, Rosenbauer says. Oral vaccines are
safe, effective, provide long-lasting protection and are inexpensive and easy
to give, he says. But in the rare instance when too few people in a community
are vaccinated, weakened strains circulating in the population can, over the
course of about a year, pick up genetic changes to become disease-causing.
The other polio vaccine is made with inactivated viral
strains and cannot cause polio. But this vaccine protects only people who get
the shots; it doesn’t offer passive immunity to others close by. “In areas
where polio is circulating, you need the oral vaccine to stop it,” Rosenbauer
Countries that have eradicated polio, including the United
States, used oral vaccines to stop widespread transmission, then switched to
the inactivated vaccine. The World Health Organization recommends this strategy
for countries that are still fighting the disease.
14, 2019 issue arrived in mailboxes wrapped in plastic.
complained about the delivery. “Plastic? Really? With everything that is known
about plastic pollution and its impacts, much of it reported in Science News,
I was astonished to see my issue arrive packaged in this way!” reader Lynn
delivered the issue in a plastic wrapper to accommodate a special offer from
one of our advertisers, says Kathlene Collins, chief marketing officer
for Society for Science & the Public, which publishes Science News.
“We will not be wrapping any future issues for subscribers in plastic,” she
says. “Thanks to our readers for the candid feedback.”
The credit for a photo of a Western meadowlark shown in “We’ve lost 3 billion birds since 1970 in North America” (SN: 10/12/19 & 10/26/19, p. 7) misspelled the photographer’s name as well as Macaulay. It should read Matthew Pendleton/Macaulay Library/Cornell Lab of Ornithology.
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