Dengue Fever and the New Dengue Vaccine

• There are 4 serotypes of the dengue virus. When infected with one serotype, the body develops immunity only to that specific serotype. Therefore, we can be infected with different serotypes of the dengue virus on different occasions. 
• The dengue vaccine is 80.2% effective in preventing dengue fever from all serotypes and reduces hospitalization by 90.4%. It can be administered to individuals aged 4 to 60 years without the need for a prior immune system test. 
• The vaccine is safe, and any side effects encountered are generally mild, such as pain at the injection site, headaches and muscle pain, with these side effects usually subsiding within 1-3 days.

The dengue virus has 4 serotypes: DENV-1, DENV-2, DENV-3, and DENV-4. Typically, dengue fever presents with mild symptoms or may even be asymptomatic. However, in some cases it can lead to severe symptoms, progressing to shock and even death. It is a disease that is difficult to predict whether an individual will experience mild or severe symptoms.

The 4 serotypes of the dengue virus circulate and alternate in causing outbreaks, which leads to varying serotypes spreading each year. However, it has been observed that the main serotypes causing outbreaks in Thailand are serotypes 1 and 2. The diversity in outbreaks means that our immunity might not cover all circulating serotypes, as infection with one serotype only provides long-term immunity to that specific serotype. Temporary cross-protection against other serotypes might occur, but it is possible to get infected with different serotypes of the dengue virus at different times throughout our lives.

If a second infection with the dengue virus occurs from a serotype different from the first infection, it may increase the risk of experiencing more severe symptoms. This is because a second infection triggers an immune response to the previously encountered serotype, which is not effective at preventing the disease. This allows the dengue virus to spread more easily, leading to increased severity of symptoms, meaning a second infection is more likely to result in more severe symptoms than the initial infection.

The Aedes mosquito is the carrier that transmits the dengue virus. These mosquitoes tend to thrive in warm climates. Hence, whether in urban or rural areas, as long as there are people residing, the Aedes mosquitoes that carry the disease can breed and grow. This means that anybody can contract the virus at any time.

Diseases like dengue fever, Chikungunya, Zika virus, malaria, and other viral infections such as the common cold or even COVID-19, can sometimes lead to confusion regarding their symptoms.

Dengue fever, Chikungunya, and Zika virus are diseases caused by viruses transmitted by mosquitoes which typically bite during the daytime. Malaria, too, is transmitted by mosquitoes but the infection is caused by a parasite. Each of these diseases can manifest a wide range of symptoms, including fever, headaches, muscle pain and joint pain. While the common cold and COVID-19 can both initially cause symptoms synonymous with dengue fever, they also involve symptoms that differ from dengue, such as coughing, shortness of breath, loss of taste or smell, sore throat, runny nose and gastrointestinal symptoms.

Furthermore, it's important to note that mosquitoes are not involved with the spread of the common cold or COVID-19, with transmission of these diseases occurring through direct contact with infected individuals.

Diseases / Symptoms	Dengue Fever	Chikungunya	Zika virus	Malaria	Influenza	COVID-19
Incubation period before symptoms present	2-14 days after a mosquito bite	3-7 days after a mosquito bite	3-14 days after a mosquito bite	7-30 days after a mosquito bite	1-4 days after contact with virus	2-14 days after contact with virus
Fever
Headaches
Joint pain
Muscular pain
Rash
Fatigue
Nausea and vomiting
Chills
Joint inflammation
Eye inflammation

While the table above shows that these diseases might present similar symptoms, their severity varies significantly which makes self-diagnosis a challenge. If you experience these symptoms and suspect it could be dengue fever, it is important to consult a medical professional promptly as they can conduct tests to confirm whether it is indeed dengue fever or another illness. This will ensure appropriate and suitable treatment can take place thereafter. 

• A new type of dengue fever vaccine can be administered to both children and adults aged between 4 and 60 years.
• The vaccine prevents dengue fever from all serotypes at a rate of 80.2% and in preventing hospitalization at a rate of 90.4%.
• It is simple and convenient to administer, requiring only 2 doses spaced 3 months apart. It can be given whether or not an individual has previously had dengue fever, eliminating the need for prior immunity screening. It is recommended that individuals who have recovered from dengue fever wait for a minimum of 6 months before receiving the dengue fever vaccine.
• The vaccine is safe, and the observed side effects are generally mild, such as localized pain at the injection site, headaches and muscle pain. These side effects mostly resolve on their own within 1-3 days.