Abstract
Introduction: Measles vaccination programme has been the cornerstone for control and prevention of measles. It provides long term immunity, interrupts the transmission of indigenous measles virus and has been successful in reducing measles-related disease and death worldwide. Two doses of measles-containing vaccine (MCV) are 97% effective in preventing measles, qualifying MCV as one of the most effective vaccines ever developed. Measles vaccine coverage in Negeri Sembilan exceeding the 90-95% range for herd immunity for measles that supposed to be effective to eliminate measles. To prove that we are in the right tract to eliminate measles, high quality case-based surveillance of measles is critical. This study aims to evaluate the outcome of measles case-based surveillance in Negeri Sembilan.
Methods: A cross sectional study of 5-year measles surveillance data for the period 2017-2021, was extracted from SM2 measles surveillance database for Negeri Sembilan. Laboratory-confirmed measles cases classified based on serology result and clinical criteria. Those recently received measles vaccine and fulfilled all the criteria for vaccine-associated measles (VAM) will be excluded. However, no genotyping was done. Viral isolation sent for those presented early within five days from rash onset.
Results: Throughout the 5-year period, 1,293 cases notified as suspected measles in Negeri Sembilan. From all cases notified, 80 cases classified as lab-confirmed measles with positivity rate of 6.2%. 1,183 discarded as non-measles and 30 cases classified as VAM. Regarding vaccination status for lab-confirmed measles, 45 cases already vaccinated. 24 cases received their single dose vaccine within 3 months from infection, 14 cases just completed 2 doses of vaccination within 5 years and 7 cases completed 2 doses vaccine for more than 5 years. Unfortunately, multivariate analysis showed vaccination status is not a significant protective risk factor for lab-confirmed measles (2 doses vaccine: OR 0.306, 95% CI 0.033-2.812; 1 dose vaccine: OR 6.244, 95% CI 0.029-1342.34). These contradictory findings might be contributed by the possibility of false classification of cases.
Discussion: Measles infection among those vaccinated is very unlikely since it conferred a long-lived immunity. The current practice in classifying measles based on serology should be revised. False positive results may occur in certain viral coinfections such as rubella, parvovirus B19, human herpes virus 6 and VAM. Measles case-based surveillance should be enhanced through integration of epidemiological and laboratory component. Positive cases must be verified using advanced testing such as genotyping or PCR test. Highly accurate testing is required to confirm the diagnosis, to determine the origin of the virus and to distinguish vaccine strains from wild-type measles virus. This is extremely important to determine our progress towards measles elimination through sensitive, complete and accurate definition of laboratory confirmed measles.
Links
- https://apcph.cphm.my/wp-content/uploads/2022/07/APCPH2022-O-21.pdf
- https://apcph.cphm.my/events/oral-session-9-ballroom-C/
BibTeX (Download)
@proceedings{APCPH2022-O-21,
title = {Enhancing High Quality Case-Based Surveillance as Elimination Strategy For Measles. Have we done enough?},
author = {Shahdattul Dewi Nur Khairitza Taib and Muhammad Nur Habibullah Malik Radzuan and Mohammad Faid Abd Rashid and Ammar Amsyar Abdul Haddi and Abdul Rahman Dashuki and Norjeehan Junadi},
url = {https://apcph.cphm.my/wp-content/uploads/2022/07/APCPH2022-O-21.pdf
https://apcph.cphm.my/events/oral-session-9-ballroom-C/},
year = {2022},
date = {2022-08-01},
urldate = {2022-08-02},
issue = {7},
abstract = {Introduction: Measles vaccination programme has been the cornerstone for control and prevention of measles. It provides long term immunity, interrupts the transmission of indigenous measles virus and has been successful in reducing measles-related disease and death worldwide. Two doses of measles-containing vaccine (MCV) are 97% effective in preventing measles, qualifying MCV as one of the most effective vaccines ever developed. Measles vaccine coverage in Negeri Sembilan exceeding the 90-95% range for herd immunity for measles that supposed to be effective to eliminate measles. To prove that we are in the right tract to eliminate measles, high quality case-based surveillance of measles is critical. This study aims to evaluate the outcome of measles case-based surveillance in Negeri Sembilan.
Methods: A cross sectional study of 5-year measles surveillance data for the period 2017-2021, was extracted from SM2 measles surveillance database for Negeri Sembilan. Laboratory-confirmed measles cases classified based on serology result and clinical criteria. Those recently received measles vaccine and fulfilled all the criteria for vaccine-associated measles (VAM) will be excluded. However, no genotyping was done. Viral isolation sent for those presented early within five days from rash onset.
Results: Throughout the 5-year period, 1,293 cases notified as suspected measles in Negeri Sembilan. From all cases notified, 80 cases classified as lab-confirmed measles with positivity rate of 6.2%. 1,183 discarded as non-measles and 30 cases classified as VAM. Regarding vaccination status for lab-confirmed measles, 45 cases already vaccinated. 24 cases received their single dose vaccine within 3 months from infection, 14 cases just completed 2 doses of vaccination within 5 years and 7 cases completed 2 doses vaccine for more than 5 years. Unfortunately, multivariate analysis showed vaccination status is not a significant protective risk factor for lab-confirmed measles (2 doses vaccine: OR 0.306, 95% CI 0.033-2.812; 1 dose vaccine: OR 6.244, 95% CI 0.029-1342.34). These contradictory findings might be contributed by the possibility of false classification of cases.
Discussion: Measles infection among those vaccinated is very unlikely since it conferred a long-lived immunity. The current practice in classifying measles based on serology should be revised. False positive results may occur in certain viral coinfections such as rubella, parvovirus B19, human herpes virus 6 and VAM. Measles case-based surveillance should be enhanced through integration of epidemiological and laboratory component. Positive cases must be verified using advanced testing such as genotyping or PCR test. Highly accurate testing is required to confirm the diagnosis, to determine the origin of the virus and to distinguish vaccine strains from wild-type measles virus. This is extremely important to determine our progress towards measles elimination through sensitive, complete and accurate definition of laboratory confirmed measles.},
howpublished = {published online at https://apcph.cphm.my},
note = {Type: ORAL PRESENTATION; Organisation: Port Dickson District Health Office; Negeri Sembilan State Health Department},
keywords = {lab-confirmed measles, positive measles serology, vaccine-associated measles},
pubstate = {published},
tppubtype = {proceedings}
}