Vaccination Against Flu and Shingles
Advisory by Marcus Heng, Guardian Pharmacist
Vaccines are one of the most effective methods to immunise against some highly contagious and debilitating diseases. Most vaccines involve inducing active immunity. Such immunity involves exposing the body to a non-infective form of the pathogen in part or whole. This triggers a long-term immune response against the vaccinated disease in future. Although most vaccines are available as injectables, some are oral (e.g. polio vaccine) or intra-nasal (e.g. influenza).
Influenza (flu) is a common viral infection that is highly contagious. Not only can it spoil that holiday or work assignment, it could even lead to further health complications. In Singapore, pneumonia, which is a common complication of influenza, accounted for about 20.1% of deaths in 2017. Although vaccination awareness has increased in recent years, especially after the H1N1 outbreak in 2009, immunisation rates remain low.
It is recommended to vaccinate yourself against the flu even when you are healthy, especially if you belong to high-risk groups. These groups include regular travellers, individuals aged 65 years and above, young children below the age of 5 or people with chronic medical conditions (e.g. people with diabetes, cardiovascular diseases, HIV). Pregnant women, healthcare workers and people with COPD or asthma may benefit from flu vaccination as well.
There are three types of influenza viruses which may affect humans, classified as A, B or C. While influenza A and B can cause seasonal flu pandemics, type C is relatively mild and less contagious. Therefore, a standard flu vaccine is made to protect against both the prevalent influenza A and influenza B virus present during that flu season.
The vaccine traditionally comprises either three different flu viruses (trivalent vaccine) or four viruses (quadrivalent vaccine). This, however, does not mean that the vaccine is useless against the thousands of other flu virus strains circulating around. The vaccine can still provide cross-protection against similar viruses to those three or four vaccinated against.
Flu vaccinations take about two weeks to induce an appropriate level of immunity. Vaccinations will not cause flu itself. However, soreness at the injection site, low grade fever and muscular aches are some common symptoms one might experience after vaccination. Also, due to the seasonal mutation of the virus itself, vaccinations for flu only grant immunity for about a year.
Shingles is another disease that could be prevented by vaccination. Chickenpox and shingles are caused by the same virus, the varicella-zoster virus (VZV). After the first chickenpox infection, the virus lies dormant in a person’s nerves. It can then reactivate as shingles later in life. About 1 in 3 people develop shingles after chickenpox and the risk increases with age and decreasing immunity. According to the 2016 Clinical Practice Guidelines on Adult Vaccination in Singapore, Tthe current recommendation is for those above 60 years old to vaccinate.
Although shingles is rarely deadly, it can lead to serious complications which may compromise our quality of life. The most common complication is called post-herpetic neuralgia (PHN), where severe pain persists for months to years in an area of shingles rash even after the area has healed over.
Shingles vaccination can reduce the risk of developing the disease by about 50% for those 60-69 years old. Although it is still possible to get shingles after vaccination, the vaccine also reduces the chances of developing PHN by almost 70%. Moreover, unless there is an on-going shingles flare, a person who has received the vaccine is not contagious.
AAfter vaccination, some might experience a chickenpox-like rash or pain at the injection site or mild headaches, but no serious side effects have been associated with the vaccine. Currently only an injectable vaccine is available. A typical vaccination immunises for at least 6 years.