Vaccination Rates for US Children Remain Generally High, But Measles Outbreaks Underscore Shortfalls in Some Regions

Although US childhood immunization rates are generally high, areas where coverage is not optimal are vulnerable to outbreaks of infections such as measles. ( Image: Dmitry Naumov/iStockphoto.com)

Although US childhood immunization rates are generally high, areas where coverage is not optimal are vulnerable to outbreaks of infections such as measles. (Image: Michael Zhang/iStockphoto.com

Although results from a federal survey indicate that overall vaccination coverage among US children remains high, areas where immunizations fall short of recommended levels are a concern and recent increases in measles cases around the country underscore that concern, say experts from the Centers for Disease Control and Prevention (CDC).

Immunization rates vary by state, according to the 2012 National Immunization Survey (NIS),  leaving some areas vulnerable to outbreaks of measles and other vaccine-preventable diseases. The 2012 NIS found that about 90% of children aged 19 to 35 months completed recommended vaccinations and less than 1% received no vaccines at all.

“These are really good results, but there is opportunity for improvement,” said Anne Schuchat, MD, director of the CDC’s National Center for Immunization and Respiratory Diseases, at a recent press briefing.

Outbreak Warning Sign

Schuchat noted that in 15 states, measles, mumps, and rubella (MMR) coverage is below 90%, a level that is a “warning sign that outbreaks may occur or that the state as a whole may be becoming vulnerable,” she said. The survey results also highlight the need to improve vaccination rates during the second year of life.

Public health officials presented the NIS results in conjunction with the 20th anniversary of the Vaccines for Children program, which provides vaccines to children from low-income families. The program was created in response to a resurgence of measles during 1989 to 1991, when 55 000 cases of measles and 123 measles-associated deaths were reported in the United States. Unvaccinated preschool-age children, many from low-income families, were disproportionately affected. According to Schuchat, such children were not being vaccinated because their families didn’t have insurance and their doctors were referring them to health department clinics to get their shots.

“As a country, as a health care system, we were missing opportunities to vaccinate these children in their medical homes,” said Schuchat.

Recent Increases in Measles Cases

Schuchat also provided a summary of recent increases in measles cases around the country. This year, from January 1 to August 24, 159 measles cases have been reported in the United States, the second-largest number of cases identified since 2000. Among the 159 cases, 157 (99%) were import-associated (were in persons who acquired the infection while outside the United States and others in the United States who were exposed to these individuals); 2 had an unknown source. About 37% of the cases occurred in children younger than 5 years; 11% were infants younger than 12 months, who are too young to be routinely vaccinated. Seventeen cases required hospitalization.

Although the 2013 cases are “a far cry from that crisis that we had 24 years ago,… things can change very quickly with measles,” Schuchat warned. “We need to stay ahead of this virus, which means we need to make sure that immunization coverage is high everywhere.”

Measles cases this year have been reported in 16 states, most of them in New York, North Carolina, and Texas. New York City reported 58 cases, which Schuchat says is the largest outbreak reported in the United States since 1996. None of the case patients from New York received MMR vaccine.

Overall, among 140 US residents who acquired measles, 117 (84%) were unvaccinated, and 11 (8%) had unknown vaccination status. Of those who were unvaccinated, 92 (79%) had philosophical objections to vaccination, and 15 cases (13%) occurred among infants younger than 12 months who were not eligible for vaccination.

“As these outbreaks are showing, clusters of people with like-minded beliefs leading them to forego vaccines can be susceptible to outbreaks when measles outbreaks are imported from elsewhere,” said Schuchat. Furthermore, she added, very high rates of immunization are needed to protect the most vulnerable—children too young to be vaccinated and those who cannot be vaccinated because of health conditions.

A clinician’s recommendation is the strongest influence on what a parent decides to do about vaccinating their children, said Schuchat. “It’s also important for clinicians to listen and to make sure they understand what concerns and questions the parents have and that they address them and take them seriously,” she said. “Because, bottom line, the parents want to keep their children healthy and they want good information in order to do that.”

This year is on track to be the worst for measles in more than a decade, according to new numbers released Thursday by the US Centers for Disease Control and Prevention. Health officials say people who refuse to vaccinate their children are behind the increasing number of outbreaks.



Categories: Immunization, Infectious Diseases, Public Health

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