CHP investigates imported case of measles infection and reports investigation progress of two previously announced cases of measles infection
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The new case involves a 57-year-old female with good past health. She developed tiredness, generalised weakness, muscle pain and headache since March 16 and rash since morning on March 20. She attended the Accident and Emergency Department (AED) of Pamela Youde Nethersole Eastern Hospital (PYNEH) in the afternoon on the same day and was later admitted for treatment. Her respiratory and blood specimen samples tested positive for the measles virus upon nucleic acid testing and immunoglobulin M (IgM) antibodies to measles virus respectively. The patient is in stable condition and has been discharged. According to information provided by the patient, she travelled to Malaysia from March 4 to 15 during the incubation period. The patient did not have contact with measles patients in Hong Kong and the case has been identified as an imported case.
The CHP is actively conducting epidemiological investigation and it was revealed that the patient had visited the following venues during the communicable period:
- King Yat Hin, 8/F, Harbour Plaza Metropolis, 7 Metropolis Drive, Hung Hom from 7pm to 10pm on March 19 (attended the anniversary dinner for MTRC staff);
- Waiting hall of the AED of PYNEH from 2pm to 3pm on March 20.
As measles is highly infectious and the transmission risk at crowded environment is higher (especially for those who have not completed measles vaccination), the CHP has set up an enquiry hotline (2125 2371) for contact tracing of the case and appealed to persons who had visited the abovementioned venues during the said period of time (including staff of the venues) to call the hotline. Officers of the CHP will assess their conditions and offer suitable advices. The hotline will operate from 9am to 5.30pm starting from tomorrow (March 27), Monday to Friday (excluding public holidays). The CHP is continuing its contact tracing and follow up investigation with the patient's working unit and hospital she was admitted.
Separately, Hong Kong Adventist Hospital – Tsuen Wan earlier reported a case of measles infection involving a 14-month-old girl. Her blood sample tested positive for the measles virus upon nucleic acid testing and IgM antibodies testing at the hospital by that time. Upon the notification, the CHP has conducted epidemiological investigations and adopted prevention and control measures (including contact tracing and providing health and medical surveillance advice to the contacts). The CHP later arranged the sample for genetic sequence typing at its Public Health Laboratory Services Branch. It was found that the sample tested positive for IgM antibodies while tested negative for nucleic acid testing, which is inconsistent with that of Hong Kong Adventist Hospital – Tsuen Wan. The CHP then reevaluated the case. Upon seeking advice from experts, the CHP confirmed that it is not a measles infection case. The CHP could not exclude that the earlier measles vaccination of the girl contribute to the abovementioned inconsistent sample testing results.
According to the latest test results, the CHP will also delete another epidemiologically linked case announced on the same day. The CHP has approached Hong Kong Adventist Hospital – Tsuen Wan and requested further information so as to understand the testing procedures of samples and the reasons for the positive nucleic acid test results of measles virus. The CHP has already notified the family members of the girls of the review results as well as removed the medical surveillance of the contacts.
After removing the two cases above, a total of six cases of measles infection have been recorded in Hong Kong this year (four of them being imported cases), while there were one to three cases annually from 2020 to 2023. According to the World Health Organization (WHO), the number of measles cases had risen worldwide over 300 000 cases reported in 2023, a roughly 80 per cent increase from 2022. The Western Pacific region recorded a total of about 5 000 cases in 2023 which represented more than 2.5 times increase when compared with 2022, with persistent transmission found in the Philippines and Malaysia. In view of the continuous increase in measles cases, the WHO has urged parents to bring their children to get vaccinated as early as possible to prevent measles from spreading.
The CHP reiterated that vaccination is the most effective way to prevent measles. During the COVID-19 pandemic over the past three years, parents, schools and healthcare workers in Hong Kong continued to support childhood immunisations, striving to maintain the immunisation coverage rates at a high level. As revealed by the vaccination uptake of primary school students and the findings of the territory-wide immunisation surveys regularly conducted by the DH, the two-dose measles vaccination coverage has been consistently maintained at a high level, well above 95 per cent, and the local seroprevalence rates of measles virus antibodies reflect that most of the people in Hong Kong are immune to measles. On the whole, the information available indicates that the risk of large-scale outbreak is considered to be low in Hong Kong. However, it is possible for some not fully vaccinated people to get infected and transmit the measles virus to susceptible people (including children aged below one who are not due for the first dose of measles vaccine).
A spokesman for the DH reminded members of the public that delays in vaccination will weaken the protection for children against measles, and parents are reminded to maintain up-to-date vaccination for their children for comprehensive and timely protection. All people who are non-immune to measles, especially foreign domestic helpers, people working or studying in tertiary institutions, and workers of sea/land/air border control points who may be at higher risk of contracting an imported case, should receive two doses of measles-containing vaccine. In general, people can be considered as non-immune to measles if they (i) did not have the infection confirmed by laboratory test before, and (ii) had not received two doses of measles-containing vaccines in the past, or have unknown vaccination status or unknown immunity against measles. On the other hand, as measles was endemic in Hong Kong and most parts of the world before 1967, people born before 1967 are considered to have acquired immunity to measles through natural infection.
The spokesman supplemented that, members of the public who are planning to travel to places with a high incidence or outbreaks of measles should review their vaccination history and past medical history, especially people born outside Hong Kong who might not have received a measles vaccination during childhood. Those who have not received two doses of measles-containing vaccines, with unknown vaccination history or unknown immunity against measles, are urged to consult their doctor for advice on vaccinations at least two weeks before departure.
Measles is a highly infectious disease caused by the measles virus. It can be transmitted by airborne droplets or direct contact with nasal or throat secretions of infected persons, and, less commonly, by articles soiled with nose and throat secretions. A patient can pass the disease to other persons from four days before to four days after the appearance of a skin rash.
The spokesman advised, "The incubation period (the period from infection to appearance of illness) of measles ranges from seven days to 21 days. Symptoms of measles include fever, skin rash, cough, runny nose and red eyes. If symptoms arise, members of the public should wear surgical masks, stop going to work or school and avoid going to crowded places. They should also avoid contact with non-immune persons, especially persons with weakened immunity, pregnant women and children aged below one. Those suspected to have been infected are advised to seek medical attention as early as possible and reveal relevant contact history of measles to healthcare professionals."
Besides being vaccinated against measles, members of the public should take the following measures to prevent infection:
- Maintain good personal and environmental hygiene;
- Maintain good indoor ventilation;
- Keep hands clean and wash hands properly;
- Wash hands when they are dirtied by respiratory secretions, such as after sneezing;
- Cover the nose and mouth while sneezing or coughing and dispose of nasal and mouth discharge properly;
- Clean used toys and furniture properly; and
- Persons with measles should be kept out of school till four days from the appearance of a rash to prevent the spread of the infection to non-immune persons in school.
For more information on measles, the public may visit the CHP's measles thematic page. Members of the public who are going to travel can visit the website of the DH's Travel Health Service for news of measles outbreaks outside Hong Kong.
Ends/Tuesday, March 26, 2024
Issued at HKT 22:15
Issued at HKT 22:15
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