This post is on Healthwise
BY KASMIAH MUSTAPHA - 14 OCTOBER 2014
An expert tells Kasmiah Mustapha about the importance of vaccination and dealing with infectious diseases
AN epidemiologist and expert on preventive medicine, Dr Eddy Bresnitz has led numerous emergency response efforts throughout his career, including the West Nile and SARS outbreaks and anthrax attack.
An advocate for disease prevention and global health, he is a firm believer in vaccination as a life-saving intervention that can help prevent sickness, disability and death.
Currently the executive director of Adult Vaccines and Global Medical Affairs and Policy at Merck, Dr Bresnitz talks about dealing with infectious diseases and the importance of vaccination.
How can we prevent the outbreak of infectious diseases?
The simple answer is by preventing the transmission of diseases thorough a multi-faceted approach.
First and foremost, a country needs to have a comprehensive and functioning public health infrastructure to ensure the distribution of clean water and safe food, since food and water are one of the most common vehicles for disease transmission.
Second, the population, from children to adolescents to adults, needs to be vaccinated against all vaccine preventable diseases to protect the individual directly, and also indirectly through herd protection.
There has to be a good surveillance system in place to monitor the incidence of disease, track contacts of infected individuals and to respond to increases in disease incidence, including outbreaks, to target control measures.
Finally, there must be adequate medical care to provide timely isolation and treatment of individuals to reduce the risk of transmission of disease to others.
What are the challenges in dealing with emerging and re-emerging of infectious diseases?
The biggest challenge is complacency, thinking that everything is under control or what looks like nothing more than a spark is really a small fire ready to explode.
The current ebola outbreak is a good example of that. What started out as a few cases in one country has now resulted in over 3,000 reported cases with over 50 per cent mortality in at least five countries (that we know of) and no prospect of controlling the outbreak in the immediate future.
The ongoing disease transmission of this deadly virus has many contributing factors. From my perspective, the main one is lack of adequate healthcare infrastructure including healthcare facilities, personal protective equipment, personnel, and appropriate control policies.
Adding to the chaos is an apparent distrust of government, poverty and cultural norms that can facilitate the transmission of disease.
With cases of ebola and Middle East Respiratory Syndrome (MERS), there are worries that more infectious diseases will become pandemic. Is that what’s going to happen?
We have witnessed many novel disease outbreaks in the last few decades where there has been significant person-to-person spread globally.
In addition to ebola and MERS, we had SARS, pandemic H1N1 flu, dengue and chikungunya.
With increasing urbanisation, population growth and ageing, global warming, global travel, food insecurity and the prevalence of social determinants of disease — such as income inequality and differing cultural norms — and the constant evolution of biological organisms and pathogens, we can expect to continually confront infectious diseases that do not respect geopolitical boundaries.
Can vaccination protect a person from infectious disease? How does it work and are there vaccinations for all infectious diseases?
Currently, there are many vaccines capable of providing protection to individuals, targeting close to 30 different diseases. Many of these have different formulations that allow for different modes of administration (intramuscular injection, subcutaneous injection, intradermal injection, oral ingestion, nasal instillation) or are combined with other vaccines to facilitate vaccination.
But no vaccine is 100 per cent efficacious. The reasons are complex but involve some aspect or a combination of factors related to the vaccine, the infectious agent and the individual.
Vaccines tend to work better in younger people because they have younger immune systems which tend to become less responsive to vaccines with age.
This concept is called immunosenescence. Through various approaches such as higher antigen content of the vaccine, the use of adjuvants to bolster the immune response to the antigen and intradermal injection, the immune system can be stimulated to have a higher immunologic response.
If there are no vaccines, how can we protect ourselves against infectious diseases?
There are infectious diseases for which there are no vaccines or, for some reason, there are insufficient supplies of vaccines. For example, there are currently no licenced human vaccines for preventing mosquito-borne organisms such as West Nile virus, chikungunya, and malaria.
I strongly believe that the most important approach to preventing mosquito-borne diseases, even when a vaccine is available (such as yellow fever and Japanese encephalitis) is good environmental control. This lowers the risk of transmission by either reducing the disease vector, in this case the mosquito, or reducing the opportunity for contact with the individual.
Environmental control can reduce the factors which support the breeding of mosquitoes, while personal protective controls (clothing, mosquito netting and insect repellant) reduce the opportunities for mosquitoes to bite the individual.
Even if a vaccine exists, environmental and personal protection controls are equally, if not more important, in reducing the risk of disease since vaccines are never 100 per cent effective.
For food and water-borne diseases, aside from ensuring good public health infrastructure, basic things that can help are cooking food properly, washing hands before and after eating and using the bathroom, keeping an appropriate distance from people who are ill with certain communicable diseases, practicing safe sex and other measures.
Dengue cases here are on the increase annually. What is your advice for dealing with this?
With climate warming, the natural habitat for mosquitoes is increasing and dengue is the most common mosquito-transmitted disease.
Dengue transmission has increased thirty-fold in the last 50 years and has been reported in over 100 countries globally, with estimates of as many as 528 million cases annually. The reasons are already mentioned earlier. Without a licensed vaccine, (although there is one in the horizon with demonstrated efficacy in clinical trials in Asia and Latin America), the major approaches to prevention are as discussed in the above answer.
Do adults need vaccination? If so, what types of vaccination should they have?
Vaccination is important for disease prevention throughout our life cycle. Many countries, including Malaysia, US, Australia, Canada, and the UK, have comprehensive recommendations for vaccinating adults. There are many vaccines which are currently licensed for preventing disease in adults. They should consult a doctor to find out what is best for them.
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