I recently attended the International Interscience Conference of Infectious Diseases and Vaccines, and I would like to share some of the presentations from the session entitled “Hot Topics in Vaccines.”
CNS complications of varicella-zoster virus infection
Dr. Michelle Science of the Hospital for Sick Children, Toronto, and her associates described the spectrum of CNS complications of varicella-zoster virus (VZV) in children admitted to the hospital during 1999-2012 (J. Pediatr. 2014;165:779-85). Clinical syndromes included 26 cases of acute cerebellar ataxia, 17 of encephalitis, 16 isolated seizures, 10 strokes, 10 cases of meningitis, 2 cases of Guillain-Barré syndrome, 2 cases of acute disseminated encephalomyelitis, and 1 case of Ramsay Hunt syndrome. In children with acute nonstroke complications, neurologic symptoms occurred a median 5 days after the onset of rash, but neurologic symptoms predated the onset of rash in five cases and in two cases there were no exanthems. Time between rash onset and stroke ranged from 2 to 26 weeks (median 16 weeks). There were three deaths among the 17 (18%) children with encephalitis. Among the 39 children with follow-up at 1 year, residual neurologic sequelae occurred in 9 (23%). Only four of the children had received a VZV vaccine. Although an effective vaccine exists, neurologic complications of VZV infection continue to occur.
Dr. Michael E. Pichichero
Timely versus delayed early childhood vaccination and seizures
Dr. Simon J. Hambidge of Denver Health, Colorado, and his associates studied a cohort of 323,247 U.S. children from the Vaccine Safety Datalink born during 2004-2008 for an association between the timing of childhood vaccination and the first occurrence of seizures (Pediatrics 2014;133(6):e1492-9). In the first year, there was no association between the timing of infant vaccination and postvaccination seizures. In the second year, the incidence rate ratio for seizures after receiving the first MMR dose at 12-15 months was 2.7, compared with a rate of 6.5 after an MMR dose at 16-23 months; thus there were more seizures when MMR was delayed. The incidence rate ratio for seizures after receiving the first measles-mumps-rubella-varicella vaccine (MMRV) dose at 12-15 months was 4.95, compared with 9.80 after an MMRV dose at 16-23 months. Again, there were more seizures when MMRV was delayed. These findings suggest that on-time vaccination is as safe with regard to seizures as delayed vaccination in year 1, and that delayed vaccination in year 2 is linked to more postvaccination seizures than on-time vaccination with MMR and that risk is doubled with MMRV.
Effective messages in vaccine promotion: a randomized trial
Brendan Nyhan, Ph.D., of Dartmouth College, Hanover, N.H., and his associates tested the efficacy of various informational messages tailored to reduce misperceptions about vaccines and increase MMR vaccination rates (Pediatrics 2014;133:e835-42). Nearly 1,800 parents were randomly assigned to receive one of four interventions: information explaining the lack of evidence that MMR causes autism from the Centers for Disease Control and Prevention; information about the danger of the diseases prevented by MMR from the Vaccine Information Statement; photos of children with diseases prevented by the MMR vaccine; a dramatic narrative about an infant who almost died of measles from a CDC fact sheet. In addition there was a control group. None of the four interventions increased parents’ intention to vaccinate another child if they had one in the future. Although refuting claims of an MMR/autism link did reduce misperceptions that vaccines cause autism, it decreased intent to vaccinate among parents who had the least favorable attitudes toward vaccines. Also, photos of sick children increased belief in an association between vaccines and autism, and the dramatic narrative about an infant in danger increased belief in serious vaccine side effects. Attempts to rectify misperceptions about vaccines may be counterproductive in some populations, so public health communications about vaccines should be tested before being widely disseminated.
Silent reintroduction of wild-type poliovirus to Israel, 2013
Dr. E. Kaliner of the Israeli Ministry of Health, Jerusalem, and associates, reported that Israel has been certified as polio-free by the World Health Organization for decades and its routine immunization schedule, like the United States, consists of inactivated poliovirus vaccine only (Euro. Surveill. 2014;19:20703). At the end of May 2013, the Israeli Ministry of Health confirmed the reintroduction of wild-type poliovirus 1 into the country. Documented ongoing human-to-human transmission required a thorough risk assessment followed by a supplemental immunization campaign using oral polio vaccine.
Trends in otitis media–related health care use in the United States, 2001-2011
Dr. Tal Marom of the University of Texas, Galveston, and associates studied the trend in otitis media–related health care use in the United States during the pneumococcal conjugate vaccine (PCV) era in 2001-2011 (JAMA Pediatr. 2014;168:68-75). An analysis of an insurance claims database of a large, nationwide managed health care plan was conducted; 7.82 million children aged 6 years and under had 6.21 million primary otitis media (OM) visits. There was an overall downward trend in OM-related health care use across the 10-year study. Recurrent OM rates (defined as greater than or equal to three OM visits within 6 months) decreased at 0.003 per child-year in 2001-2009 and at 0.018 per child-year in 2010-2011. Prior to the pneumococcal conjugate vaccine (PCV-13), there was a stable rate ratio of 1.38 between OM visit rates. During the transition year 2010, the RR decreased significantly to 1.32, and in 2011 the RR decreased further to 1.01. Mastoiditis rates significantly decreased from 61 per 100,000 child-years in 2008 to 37 per 100,000 child-years in 2011. The ventilating tube insertion rate decreased by 19% from 2010 to 2011. Tympanic membrane perforation/otorrhea rates increased gradually and significantly from 3,721 per 100,000 OM child-years in 2001 to 4,542 per 100,000 OM child-years in 2011; the reasons for this are unclear.