HPV is a group of viruses which can infect the genital areas of men and women mainly through sexual contact. It is an important cause of cervical cancer and is also associated with other types of genital cancer.

Diphtheria is caused by bacteria. Affected persons may have fever, sore throat with patches of greyish membrane adhered to the throat and breathing difficulty. In serious cases, it can cause airway obstruction, heart failure, nerve damage or even death. The disease is spread by contact with patient or carrier. Less commonly, a person may get infected through contact with articles soiled with discharges from affected persons.

Both DTaP-IPV-Hib (5-in-1) and DTaP-HB-IPV-Hib (6-in-1) combination vaccines can effectively prevent diphtheria, tetanus, pertussis, polio and haemophilus influenzae type B infections. DTaP-HB-IPV-Hib (6-in-1) vaccine protects against one additional virus – Hepatitis B virus. By combining vaccines that are traditionally separate, DTaP-IPV-Hib (5-in-1) and DTaP-HB-IPV-Hib (6-in-1) combination vaccines can greatly reduce the number of vaccinations for children (from 13 to 7), thus reducing pain, discomfort and side effects, and parents' anxiety and inconvenience.

Haemophilus influenzae type b (Hib) is a bacterium which can cause serious invasive disease especially in young children. Contrary to what the name Haemophilus influenzae suggests, the bacterium does not cause influenza or flu. Hib infection usually affects children aged below five years. The risk of infection among older children is relatively low.

Pneumococcus (Streptococcus pneumoniae, or S. pneumoniae) is the most common bacterium causing respiratory infections in children. It can cause a wide range of infections from bronchitis, otitis media, sinusitis, pneumonia, septicaemia to meningitis. In Hong Kong, about 20% of pre-school children carry the bacterium in their nasopharynx. Invasive disease (pneumonia, septicaemia or meningitis) happens in 1.2/1,000 of the population. Incidence for less invasive disease is likely to be at least 10 times higher. The young and the old are the most vulnerable groups, both in morbidity and mortality. So this is a serious cause of infection for all ages.

Rotavirus is the most important cause of gastroenteritis (diarrhoea)in children and infants worldwide. In Hong Kong, it is responsible for about 30% of gastroenteritis admissions into public hospitals. It typically affects infants aged 6 – 15 months. The diarrhea caused by Rotavirus is usually more severe and tends to give rise to dehydration more often, especially in young infants. Epidemiology studies have shown that by age 2 years, almost all babies would have had at least one Rotavirus infection, and about 40% has had up to 3 infections. Globally it is responsible for over 2 million admissions and 440,000 deaths annually.

Japanese encephalitis (JE) is a mosquito-borne disease caused by the JE virus, which is transmitted to human via bites from an infected mosquito, usually the common type in Hong Kong, the Culex. The mosquito gets the virus from infected pigs and birds. The disease therefore is not transmissible among humans. Symptoms occurs after an incubation of up to 14 days, usually starting with fever and headache, followed by neurological symptoms like neck stiffness, weakness, movement disorder, impaired consciousness, coma and convulsions in the severe cases. Mortality varies from 5-35%. As there is presently no specific treatment, management is largely supportive.

Hepatitis A is a liver disease caused by the hepatitis A virus (HAV). Clinical features of hepatitis A are similar to those of other types of viral hepatitis. Typical signs and symptoms of hepatitis A include fever, malaise, loss of appetite, diarrhoea, nausea, abdominal discomfort, or jaundice (yellowing discolouration of the skin and sclera of the eyes, dark urine and pale stool).

Hepatitis B is another type of viral hepatitis that leads to acute hepatitis. It can be followed by chronic liver damage, including cirrhosis and liver cancer. It has an incubation period of 6 weeks to 6 months. About 5-10% of infected adults and 70-90% of infected infants are unable to clear the virus, therefore becoming chronic hepatitis B and serving as a source of infection to others. HBV infection occurs throughout the world. It is estimated that more than 2 billion people have been infected worldwide, of which more than 350 million have chronic liver infection. Hepatitis B is endemic in Southeast Asia. In Hong Kong, the overall prevalence of chronic hepatitis B infection is moderate. The hepatitis B virus is found in the body fluids of an infected person, mainly in the form of blood, amniotic fluid, semen and vaginal secretions. Routes of transmission include perinatal transmission, blood contact and sexual contact.
Hepatitis B Vaccination is the most effective prevention method. The complete course of vaccination takes a total of three injections. The second injection is given 1 month after the first, and the third injection 5 months after the second. About 90 to 95% of people will gain life-long immunity to hepatitis B after a full course of vaccination. Preferably have blood tests before vaccinated. Only people who have never been exposed to hepatitis B should have vaccination. Hepatitis B Vaccination is recommended for newborn, household and sexual contacts of chronic hepatitis B, intravenous drug users, people who receive blood or blood products on a regular basis, people on dialysis and health care workers who might be in contact with blood or other body fluids.

* The above information on Hepatitis B vaccine is provided by Centre for Health Protection (CHP) of the Department of Health on their website.

Measles is caused by the Measles virus and spreads through the air by droplet or direct contact with nasal or throat secretions of infected persons, and less commonly, by articles soiled with nose and throat secretions. Affected persons will present initially with tiredness, fever, cough, red eyes and white spots inside the mouth. This is followed by a red blotchy skin rash 3-7 days later. The rash usually spreads from the face down to the rest of the body. In severe cases, middle ear, lungs and brain can get involved and lead to serious consequences or even death.

Varicella (also known as chickenpox) is a viral illness caused by the varicella-zoster virus. It is highly contagious and is spread by airborne transmission of droplets from the respiratory tract or from the vesicle fluid of the skin lesions of chickenpox or herpes zoster infection. Affected persons present with fever and itchy rash.

MMRV vaccine can effectively prevent Measles, Mumps, Rubella, and Varicella (also known as chicken pox). By combining vaccines that are traditionally separate (MMR and Varicella vaccine), MMRV vaccine (compared to MMR and Varicella vaccine) has enhanced immune response and can greatly reduce the number of vaccinations for children.

Meningococcal infection is caused by a bacterium, Neisseria meningitides, or meningococcus. Thirteen serotypes are known, but 4 of them, serotypes A, B, C and W-135, may cause epidemic spread. Although less common, it can cause serious and life-threatening infections including meningitis and septicemia. For every 100 people who contract the infection, up to 15 will die even if they receive proper treatment. Permanent complications of infection include brain damage, deafness, and paralysis of limbs. Meningococcal infection spreads from person to person by coughing, sneezing, or close contact. In Hong Kong, around 5-8 children are diagnosed each year sporadically, with a death rate of around 20%. Serotypes B and C are the most common ones.

Anyone who has had chicken pox is at risk for developing shingles. It is estimated that 1 million or more cases occur each year in the United States. Shingles can occur in people of all ages and the risk increases as people get older. The causes of shingles aren't completely known, but it is thought that a combination of factors can trigger shingles, including aging and problems with the immune system.

Seasonal influenza is an acute illness of the respiratory tract caused by influenza viruses. It is usually more common in periods from January to March and from July to August in Hong Kong. Three types of seasonal influenza viruses are recognised to cause human infection, namely A, B and C. For healthy individuals, seasonal influenza is usually self-limiting with recovery in 2 – 7 days. Symptoms may include fever, cough, sore throat, runny nose, muscle pain, fatigue and headache; some may also have vomiting and diarrhoea. Cough is often severe and prolonged but fever and other symptoms generally resolve in 5 – 7 days. However, influenza can be a serious illness to the weak and frail or elderly people, and may be complicated by bronchitis, chest infection or even death. Influenza viruses mainly spread through droplets when infected people cough, sneeze or talk. The infection may also spread by direct contact with the secretions of infected persons. Incubation period is usually around 1 – 4 days. Infected persons may pass the viruses to other people 1 day before and up to 5 – 7 days after they develop symptoms. The period may be even longer in young children or severely immunocompromised persons.
Seasonal influenza vaccination is safe and effective in preventing seasonal influenza and its complications. Influenza can cause serious illnesses in high-risk individuals and even healthy persons. Given that seasonal influenza vaccines are safe and effective, all persons aged 6 months or above except those with known contraindications are recommended to receive influenza vaccine for personal protection. Usually, it is suggested that vaccination should be received in autumn every year. About 2 weeks after vaccination, the body will develop a sufficient level of antibodies to protect against influenza virus infection.
* The above information on seasonal influenza vaccine is provided by Centre for Health Protection (CHP) of the Department of Health on their website.