On March 18th, a female flight attendant was confirmed to be infected with rubella in Taiwan [1]. Before she developed symptoms, she had a travel history that included Vietnam, Indonesia, and Hong Kong [1]. After her confirmation, she was determined to be the first imported case of rubella in Taiwan this year, though the second confirmed case of rubella in the country overall, this year.
Prior to this imported case, the first case of rubella was reported on January 29, 2015 [2]. A 41-year-old male who resided in northern Taiwan was confirmed of rubella infection. Since he did not have a history of traveling outside of the country, Taiwan Centers for Disease Control (Taiwan CDC) determined his case of rubella as an indigenous one.
Health officials have identified close contacts to these cases and have placed them under monitoring. None of the first case’s contacts tested positive and the second case’s contacts were monitored until April 11th to ensure the prevention of any further outbreaks. More than 1500 people are followed for the flight attendant’s case and it has set a new record for the Taiwan CDC’s monitoring list [3].
In Taiwan, the average number of rubella cases tend to be small for these years, though the years 2007, 2008, and 2011 seem to be exceptions. These increase in cases for those years coincided and were often linked with the increase in rubella cases of other countries in Asia for those years [4]. In 2014, there were seven cases in Taiwan and six of the seven cases were imported [4, 5]. Yet, these numbers still seem to be limited compared to other countries in Asia [6].
About Rubella
Rubella is caused by a virus [7]. Symptoms of rubella infection include mild fever, rash in the face and body, swollen lymph nodes in the neck or behind the ears [7]. Further, there may be body aches, fatigue and coughing, as well as other symptoms that may resemble a common cold [7]. It is highly contagious and is transmitted through close contact with an infective case [7].
However, rubella infection is preventable through vaccination. A live attenuated rubella vaccine was introduced to Taiwan in 1986, mandated for female junior high school students [8]. In 1992, Taiwan CDC expanded to a more universal vaccination program providing Measles-Mumps-Rubella (MMR) vaccines to 15 month old children [8]. Since 2001, Taiwan CDC provides the second dose regularly for children at seven years of age before they enter school [8]. MMR vaccine coverage in Taiwan is approximately 95% among the general population [8].
Rubella & Pregnancy
Pregnant women are unable to receive vaccination during pregnancy, so it is strongly encouraged to take a blood test and see if they have enough rubella immunity [9]. It is also encouraged to wait at least a month after the vaccination to become pregnant [9].
If women who are not vaccinated or have low antibodies contract rubella during pregnancy, especially during the first trimester, the fetus may also have a chance of contracting the virus and congenital rubella syndrome (CRS) may occur [10]. Babies with CRS may have birth defects such as eye abnormalities, congenital heart disease, mental disabilities, and organ damage. Worldwide, more than 100,000 babies are born with CRS every year [10]. In Taiwan, due to effective vaccination programs, only five cases of congenital rubella syndrome (CRS) have been confirmed from 1994 to 2008 [8]. Four out of five patients’ mothers were foreigners. No confirmed CRS cases have been reported since 2009 [8].
Why Vaccination Matters
Although vaccine coverage in Taiwan is high, there is always risk of rubella resurgence due to several factors. First, there is frequent travel amongst the population, so there will always be risk of an imported case from countries with lower vaccination coverage [11]. According to the WHO, global coverage of rubella vaccine is approximately 44% in 2013 which indicates, there still are countries with lower coverage compared to other regions in the world [12]. Second, Taiwanese who were born before the country’s universal vaccine program started, are susceptible to rubella infection due to not being vaccinated. This so-called a “vaccine gap” was also one of the factors behind the rubella outbreak in Japan in 2013 [13, 14]. Third, although the vaccine coverage at the country level is high in Taiwan, there are communities with less than enough vaccine coverage (at least 80% of vaccine coverage is necessary to prevent a rubella outbreak) remain at risk of an outbreak [4, 15]. Further, MMR vaccine is effective after the first dose. The second dose assures another chance to achieve immunity for people who did not achieve immunity the first time around. If people miss receiving the second dose, some of them may also be susceptible [15].
Therefore, not only having a high percentage but maintaining high vaccination coverage is considered important. The advantage of the rubella vaccine is that although there are several genotypes of rubella virus, they share a common serotype so the current used vaccine is considered effective [16]. There may be a possibility of mild adverse events such as fever, mild rash, or swelling in the cheeks or necks, but severe adverse events are rare [15, 17]. Taiwan CDC is encouraging people who are susceptible to receive MMR vaccine and to maintain vigilance as new cases arise [4, 10].
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Sources
[2] http://outbreaknewstoday.com/taiwan-reports-years-first-indigenous-rubella-case-31708/
[3] http://www.taipeitimes.com/News/taiwan/archives/2015/03/20/2003613987
[4] http://nidss.cdc.gov.tw/en/SingleDisease.aspx?dc=1&dt=2&disease=056
[6] http://apps.who.int/immunization_monitoring/globalsummary/timeseries/tsincidencerubella.html
[7] http://www.cdc.gov/rubella/about/index.html
[9] http://www.cdc.gov/vaccines/adults/rec-vac/pregnant.html
[10] http://www.cdc.gov/vaccines/pubs/surv-manual/chpt15-crs.html
[11] http://focustaiwan.tw/news/asoc/201501300021.aspx
[12] http://www.who.int/immunization/monitoring_surveillance/global_immunization_data.pdf?ua=1
[13] http://theconversation.com/vaccination-gaps-led-to-rubella-outbreaks-in-japan-and-poland-15970
[14] http://www.nih.go.jp/niid/en/iasr-vol34-e/865-iasr/3469-tpc398.html
[15] http://www.who.int/wer/2011/wer8629.pdf?ua=1
[16] http://idsc.nih.go.jp/iasr/32/379/tpc379.html
[17] http://www.cdc.gov/vaccines/hcp/vis/vis-statements/mmr.html
