Source: Hong Kong Government special administrative region – 4
The Centre for Health Protection (CHP) of the Department of Health (DH) today (July 3) is investigating a case of measles infection and reminded the public that vaccination is the most effective way to prevent measles.
The case involves a 10-month-old baby boy who is a close contact of two epidemiologically linked measles infection cases announced by the CHP recently. During the investigation of these two cases, the CHP found that they had visited a private clinic in Jordan during the communicable period. The CHP immediately initiated contact tracing in the clinic and found that 21 people had stayed in the clinic at the same time as the two cases. Hence, they were classified as close contacts, including three high-risk individuals aged below one-year-old who have not yet reached the age to receive the first dose of the measles vaccine. The CHP explained the risk to the parents of the three children and recommended measles immunoglobulin injection to minimise the risk of infection. One of them agreed and received the injection arranged by the CHP at a hospital, and is now asymptomatic. The other two did not accept the injection arrangement (including the 10-month-old baby boy).
During the medical surveillance for the close contacts, the 10-month-old baby boy presented with fever on June 30 and developed skin rash the following day. The CHP arranged him to the Queen Elizabeth Hospital on July 1 for isolation and treatment. His respiratory specimen sample tested positive for the measles virus upon nucleic acid testing. He remains hospitalised and is in stable condition.
An epidemiological investigation revealed that the baby boy has not yet reach the age to receive the first dose of the measles vaccine. He had no travel history during the incubation period. The CHP believed that the source of infection of this case is related to the two recently confirmed measles cases.
The baby boy’s five household contacts are currently asymptomatic and are put under medical surveillance. Since two of the household contacts were uncertain whether they had received measles vaccination, the CHP has provided post-exposure vaccination for them. Another household contact is currently not in Hong Kong. The CHP has notified the relevant health authority for necessary follow-up actions. Apart from his family members, the baby boy has no other close contacts.
There are currently four cases in this cluster, including three members of a family and the above-mentioned baby boy. The remaining two members of the family and 20 other close contacts at the clinic remain asymptomatic so far and are under continuous medical surveillance. Preliminary investigations have not revealed any epidemiological linkages between this cluster and other confirmed cases previously recorded in Hong Kong.
“The incubation period of measles (i.e. the time from infection to onset of illness) is seven to 21 days. Symptoms include fever, skin rash, cough, runny nose and red eyes. When such symptoms appear, people should wear surgical masks, stay home from work or school, avoid crowded places and contact with unvaccinated people, especially those with weak immune systems, pregnant women and children under 1 year old. Those who suspect they are infected should consult their doctors as soon as possible and inform healthcare workers of their history of exposure to measles,” the Controller of the CHP, Dr Edwin Tsui, said.
“Under the Hong Kong Childhood Immunisation Programme, the overall immunisation coverage in Hong Kong has been maintained at a very high level through the immunisation services provided by the DH’s Maternal and Child Health Centres and School Immunisation Teams. As evidenced by the findings on vaccination coverage of primary school students and the territory-wide immunisation surveys conducted regularly by the DH, the two-dose measles vaccination coverage has remained consistently high, well above 95 per cent, and the local seroprevalence rates of measles virus antibodies reflect that most people in Hong Kong are immune to measles. However, Hong Kong, as a city with a high volume of international travel, still faces the potential risk of importation of the measles virus and its further spread in the local community. Hence, a small number of people who have not completed a measles vaccination (such as non-local-born people including new immigrants, foreign domestic helpers, overseas employees and people coming to Hong Kong for further studies) are still at risk of being infected and spreading measles to other people who do not have immunity against measles, such as children under 1 year old who have not yet received the first dose of the measles vaccine,” he added.
People born before 1967 could be considered to have acquired immunity to measles through natural infection, as measles was endemic in many parts of the world and in Hong Kong at that time. People born in or after 1967 who have not yet completed the two doses of measles vaccination or whose measles vaccination history is unknown, should consult their family doctors as soon as possible to complete the vaccination and ensure adequate protection against measles.
The number of measles cases in some overseas countries remains at a high level this year. The outbreaks in North America (including the United States and Canada), Europe and neighbouring areas (including Vietnam, Cambodia and the Philippines) are ongoing due to the relatively low vaccination rate. Furthermore, an increasing number of measles cases have also been recorded in Japan and Australia this year. For those who plan to travel to measles-endemic areas, they should check their vaccination records and medical history as early as possible. If they have not been diagnosed with measles through laboratory tests and have never received two doses of measles vaccine or are not sure if they have received a measles vaccine, they should consult a doctor at least two weeks prior to their trip for vaccination.
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.