A third dose of measles vaccine is needed in young Korean health care workers

Seroprevalence of Measles in Healthcare Workers in South Korea

“…Therefore, it is important to know the seroepidemiology of HCWs for policy decision making process, but there are only limited data on seroprevalence of measles of HCWs in South Korea. This study builds on our earlier publication [4] with a larger number of subjects.…”

“…Despite such measures, however, small local outbreaks of measles continued to occur in South Korea [1], and there have been some reports of pockets of under-immunity among the young adult population [23]. We previously reported the low seropositive rate from 1994 to 1985 birth cohort in new healthcare workers (HCWs) (n = 1,130) [4]. Outbreak of measles in healthcare facilities would have a serious impact as large numbers of patients and HCWs would be exposed, and serious complications of measles may develop in immunocompromised patients as a result.…”

Measles, the need for a paradigm shift

“…Measles vaccines are 60-year-old and contain viral strains belonging to the clade A, no more detected since 2008 [112] Measles live-attenuated vaccine is not as immunogenic as natural infection (primary failure) due to host factors (age, HLA), and vaccine-induced immunity is waning with time. At least 2 doses are recommended at all ages [36,41,52,53,57,74,78,79,[86][87][88][89][93][94][95][96][97] Post-vaccination antibodies may be not protective against some strains (secondary failures). Highly exposed population (healthcare workers, travellers) are of particular concern [5, 98-106, 109, 110] Measles virus antigenic stability is probably not an enduring rule [44,45,49,[115][116][117][118][119][120][121]124] Some recent measles variants have been demonstrated able to evade antibody-mediated neutralization [45, 109, 110, 114-116, 119, 120, 124] Measles virus molecular epidemiology based on genotyping targeting the N-gene misses the detection of mutations in the H and F genes that encode epitopes involved in the host response to the virus [40,43,107,127]…”

“…Compared with wild-type virus infection, the duration of immunity following measles vaccination has been proven to be more variable and shorter [41,[93][94][95]. Notably, decreasing seroprevalence in twice-vaccinated young adults has been documented, questioning the benefit of a third dose [96,97]. Case report D8 strain: phylogenetic tree based on the nucleocapsid gene from measles viruses.…”

Classification of global measles cases in 2013–17 as due to policy or vaccination failure: a retrospective review of global surveillance data

“…1,4 With the stagnation in incidence and large outbreaks occurring in populations with reported high vaccination coverage, 5,6 questions have been asked about whether the recommendation of two doses of MCV is sufficient to eliminate measles, given that some measles cases have occurred in people with documentation of having received two doses of MCV and seroprevalence is unexpectedly low among cohorts who had high reported coverage of two-dose vaccination. [7][8][9] To answer these questions, we sought to categorise whether measles cases reported across WHO member states were due to programmatically preventable causes or programmatically non-preventable causes, as was recommended in the midterm review of the measles and rubella global strategic plan for 2012-20. 10 Generally speaking, a programmatically preventable case is in somebody who should have been vaccinated with MCV according to existing recommendations, either one or two doses depending on the country's recommendation, ideally leading to induction of an active immune response, but did not receive the appropriate number of doses.…”