The COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the most severe pandemic we have faced in over 100 years. Fortunately, unlike those facing the 1918 Influenza pandemic we have the technology to develop vaccines to help us bring this pandemic under control. After the provision of clean water, vaccines are the most important and effective health strategy. For example, childhood vaccines save an estimated 2–3 million lives worldwide every year and have contributed substantially to the fall in the global infant mortality rate from 65 per 1,000 live births in 1990 to 29 per 1,000 in 2018. The benefits from vaccination can extend beyond the vaccinated individual and benefit the wider community through herd immunity.
Over the past 12 months, the scientific community has made an unprecedented effort to develop vaccines that will provide protection against this newly recognised virus. Vaccine development has been supported by political leaders and huge financial input working with scientists and pharmaceutical companies. Thanks to these efforts we now have 200 vaccines in development including at least 11 already in Phase III trials.
Vaccine development is usually stepwise and typically takes at least 10 years. There are initial studies conducted in laboratories. If these are favourable Phase 1 studies are performed involving a small number of people. This phase assesses safety, dosage and immune results. Usually just a few candidate vaccines move on to Phase II studies during which the optimal dose and schedule, as well as safety is determined. These involve studies that enrol 100 to 1,000 people. Finally, Phase III studies assessing efficacy and safety are completed. These usually involve many thousands of people. Because of the scale of this pandemic instead of the slow stepwise process of vaccine development and then manufacture scientists have combined phases, for example Phase 1 and II, with these phases happening in parallel. Corners have not been cut. Instead, the timing has simply been compressed.
As well as being accelerated in development, the vaccine search against COVID-19 has included some new technologies. While some candidate vaccines use classic methods such as inactivated virus others are using modern platforms including recombinant protein (e.g. whole spike protein) and inactivated viral vectors (various human or chimpanzee viruses which cannot multiply in the cells of the vaccinated person but express the spike protein). In addition, there are some vaccines that have been developed using new methods such as mRNA-based vaccines which have not previously been used for a licensed vaccine. This technology seems to produce a particularly effective vaccine and also one that can be manufactured in large amounts rapidly.
The COVID-19 vaccines all aim to make the vaccine recipient develop protection against the spike protein on the surface of the SARS-CoV-2 virus. This spike protein is vital for the virus to enter a person’s cells and thus invade the body. If the protection induced by vaccination prevents this step, illness won’t follow. The different types of vaccines will differ in how effective they are, in the side effects they cause and duration of protection etc. Different vaccines may work better in different age groups or populations.
Initial study data has focussed on whether a candidate vaccine protects the person who has received the vaccine from COVID-19 illness rather than prevention of infection with the SARS-CoV-2 virus. Therefore, we do not yet know how well these vaccines will be able to prevent someone who receives the vaccine, who is then exposed to the SARS-CoV-2 virus, from being able to spread the virus to another person. This information will come in the next few months.
It is exciting that New Zealand currently has orders for 4 different COVID-19 vaccines. In my next blog I will provide information about how these vaccines work and what we know about them so far.
A recent publication on the risk of COVID-19 during flights caught my eye as safety on flights will be paramount if international air travel is to return in this COVID-19 era. The paper described well documented flights where COVID-19 was spread onboard. While many of the cases were passed to those in close proximity to the infected travellers some infections were passed to those more than 3 rows away. (For other respiratory infections spread on planes is generally confined to 2 rows from the infected person as the ventilation system is very effective.) However, the paper presents good news on the effectiveness of masks at reducing the risk on flights. On the flights with documented transmission masks were not mandated and rarely used. On the other hand, on 5 flights lasting 5 hours carrying a total of 58 infected passengers no secondary cases were identified on day 14 screening of the many other passengers. These flights are very encouraging. Although more studies are needed this information suggests that careful mask use during flights significantly reduces the risk of COVID-19 transmission. Obviously, the flight is not the only risk period of a journey and care needs to be taken every step of the way during travel.
Concern both locally and internationally has been expressed about the impact of COVID-19 on routine vaccination coverage. The World Health Organization has made a plea for vaccination programmes to not be interrupted by the COVID-19 pandemic. Maintenance of high coverage and timely delivery of national immunisation schedules is necessary to prevent outbreaks of illnesses such as measles and polio.
In America it has been shown that vaccine coverage of all age groups has dropped during the COVID-19 pandemic. For example, in the week of April 6th this year (near the height of the COVID-19 pandemic in the United States) compared with that week in 2019, vaccination rates were 56% lower for all ages. The decrease was greatest for adults aged 65 and older where vaccine coverage decreased by 83 %.
I urge you to catch up on missed vaccinations for infants, children, adolescents, pregnant women, those over 65 years and those for whom influenza vaccine is recommended. I also recommend that you make plans to see your GP for chronic disease visits and screening for other conditions if you have missed them.
The number of cases of malaria diagnosed in the Americas fell from 2005 to 2014 but over the past few years they have increased mainly because of increased cases in Venezuela because of decreased control activities there over the past 10 years.
Paraguay and Argentina have been certified malaria free by WHO in the past year and El Salvador has not reported a locally acquired case in almost 3 years. Belize has had no cases and Costa Rica under 100 cases this year. Guatemala and Honduras are reporting significant decreases in malaria cases with Honduras having fewer than 300 cases this year. Most malaria in Brazil is in the Amazon region and cases have decreased this year compared with last year. Haiti, Peru, Suriname and Nicaragua have also had reduced numbers of cases compared with last year. In Ecuador three provinces - Morona Santiago, Pastaza and Orellana have 84% of the cases with no risk in the Andes or west of them.
On the other hand, out breaks of malaria are occurring in Colombia with increased cases compared with last year in the departments of Chocó, Nariño, Córdoba, Norte de Santander, Meta, and Cauca. In Dominican Republic there are outbreaks in La Ciénega and Los Tres Brazos, which includes municipalities in the Santo Domingo and San Cristóbal provinces and some neighbourhoods in the National District. In Panama, outbreaks have been reported in four regions: Guna Yala, East Panama, Ngãbe Buglé, and Darién. Finally, thousands of cases are being seen in Venezuela with the states of Amazonas, Bolívar, and Sucre reporting the highest number of cases.
Thus, many travellers visiting Central and South America do not need malaria prophylactic medications. The situation is fluid though as the considerably increased number of cases in Venezuela may spill over into neighbouring countries as people travel across borders sometimes taking malaria with them to receptive areas. Outbreaks can then occur in areas where eradication has been achieved.
The theme of the Conference of the International Society of Travel Medicine I attended in June was Travel Medicine in a Changing Climate. We heard depressing statistics about how climate change exacerbates existing threats and acts as a threat multiplier and particularly affects people living in marginal areas who are already vulnerable. Disasters caused 61 % of the 28 million displacements that occurred last year. Interactions between climate and infections are very complex and poorly understood. For example, with increasing temperatures in Africa malaria may decline and dengue increase as the optimal temperatures for the different mosquitoes that transmit the two illnesses differ.
A more encouraging speaker was the one on Making Tourism Sustainable. She told us about the Global Sustainable Tourism Council (GSTC) which is a non-profit organisation which recognises that tourism has the potential to do harm but endeavours to make tourism beneficial. It has established Global Sustainable Tourism Criteria. These are “the guiding principles and minimum requirements that any tourism business or destination should aspire to reach in order to protect and sustain the world’s natural and cultural resources, while ensuring tourism meets its potential as a tool for conservation and poverty alleviation.” Before we travel we should think about our destination and activities carefully. We should think about our mode of transport and if flying offset our carbon. Is our accommodation or tour operator GSTC accredited? Pack lightly to reduce our carbon and take reusable drink bottles and coral safe sunscreens. We should learn some local language, pay the price (not haggle) and respect the natural environment.
Measles cases are rising alarmingly in many areas but I wrote about that last July. I am thus going to discuss the increased risk of dengue in many popular tourist destinations. Dengue comes in waves every few years. Cases are currently increased in Vietnam and Singapore is having an outbreak. Dar es Salaam in Tanzania is as well. Closer to home Timor Leste, Palau, Vanuatu, New Caledonia, Tuvalu, French Polynesia and Cook Islands have increased numbers of cases. Fiji may too as travellers have been diagnosed after trips there recently.
Mosquito bite avoidance is the only protection against dengue. It is day biting ones that are responsible and they may be in urban areas as the out break in Singapore illustrates. The first dengue vaccine in use has now been approved in America for people with a documented prior dengue illness who live in dengue areas. There are more dengue vaccines in the pipeline so in the future vaccination may become a strategy for travellers. Until then use your repellent.
Unfortunatley we currently have a rabies vaccine shortage in New Zealand. This is causing some restrictions on preexposure prophylaxis. Remember that mammal bites in most countries of the world carry a risk of rabies and should be avoided. Travellers are more likely to be bitten in Asia than Africa or the Americas as there are many opportunities to mix with dogs and monkeys. The risk of a mammal having rabies is highest in Africa as dog vaccination there is low. Dog bites are the most common followed by monkeys. Children are more likely to be bitten than adults and as their bites are often on the face which has many nerves the bites are a higher risk.
Always keep away from pets especially those eating, sleeping or with babies. Avoid contact with free roaming mammals and stay away from bats. Don’t try to run away from dogs but stand still and avoid eye contact. If you fall over curl up and stay still. It is better not to visit monkey beaches or temples and if you do certainly don’t take any food with you. Again, staring them in the eye is a sign of aggression. Many bats have tiny teeth and wounds may not be readily apparent. Any suspected or documented bite or wound from a bat is a reason for seeking post bite treatment.
If bitten or scratched by a mammal wash the injury with copious amounts of water and finish with something like betadine. Then seek medical care as soon as possible. Vaccination with cell cultured vaccines following a WHO approved schedule should be started and in addition WHO category 3 injuries (single or multiple transdermal bites or scratches, contamination of mucous membrane or broken skin with saliva from animal licks, exposures due to direct contact with bats) should be injected with rabies immunoglobulin. This may not be available at the first medical centre you go to but you should go somewhere bigger until you find some. Thailand is a country with excellent post bite management so although many people are bitten there deaths from rabies are low.
Pretravel rabies vaccines make it easier if someone is bitten. They already have antibodies so just need 2 doses of vaccine to boost their protection after an injury and don’t need immunoglobulin. Remoteness from healthcare, planned activities and duration of travel are all factors to consider when deciding whether to be vaccinated before travel.
In the past Venezuela was admired for its healthcare system and public health infrastructure. Unfortunately, the past few years have changed that. There is now food insecurity with malnutrition, the health care system has collapsed and there has been a massive exodus of health care workers. Infant and maternal mortality have increased and infectious diseases previously controlled or eliminated have returned. The flow of people from Venezuela to neighbouring countries is affecting their rates of infectious diseases too. For example, the continent had controlled measles however between January and December of last year there were over 5,600 cases in Venezuela, more than 2,000 cases in Colombia and over 10,000 in Brazil. Those in Colombia and Brazil were linked with Venezuelan migrants. There have been 1,000 cases of diphtheria (another vaccine preventable disease essentially eliminated) since January 2018 in Venezuela. In 1961 WHO recognised Venezuela for eliminating malaria in densely populated areas. The past few years have seen a resurgence. Between 2015 and 2016, reported cases increased by over 75%, from 136 402 to 240 613. There is a severe shortage of antimalarials and control efforts have stopped. HIV and TB are other infectious diseases increasing and being taken by migrants to neighbouring countries. These two diseases need good medical care to treat patients and to reduce spread. The current situation is thus a huge crisis which needs urgent attention for the health of the region and of those who travel there .
Prior to 2014 Ebola outbreaks were usually small and in remote areas and thus controlled relatively easily once recognised. The outbreak in 2014, however, occurred in urban areas and caused nearly 30,000 cases and over 13,000 deaths. In addition, the World Bank estimated that the West Africa epidemic cost the three affected countries $2.2 billion in lost gross domestic product in 2015. Ebola is again spreading in urban areas, this time in the Democratic Republic of the Congo. Since September, the incidence of Ebola has more than doubled and the outbreak is now the second largest one to date. The virus has spread to 11 DRC health zones, and the WHO has deemed the risk of further national and regional spread to be very high. The majority of people with recently diagnosed Ebola were not on existing lists of contacts of people with the disease. This concerningly indicates unrecognized transmission in the community. Control efforts are being hampered by civil unrest, armed conflict, inadequate infection prevention and control in healthcare settings and community resistance. No cases have been reported in neighbouring countries to date but if the outbreak continues the risk of spread is high particularly to Uganda and also Rwanda and South Sudan. Heightened surveillance has been implemented in Burundi, Rwanda, South Sudan, and Uganda. Unlike previous outbreaks vaccination is being trialed with over 53,000 people being vaccinated in affected areas. In addition, experimental treatments are being used.
Sexual transmission may occur even in men with no symptoms of the infection. Previously it was recommended that men who have travelled to zika areas abstain or use condoms for 6 months to avoid infecting their partners. This was based on finding virus material in semen for more than 3 months in some cases. Newer information shows that live virus stops being in semen by one month usually. The new recommendation is: that men with possible Zika virus exposure who are planning to conceive with their partner wait at least 3 months after symptom onset or their last possible Zika virus exposure before engaging in unprotected sex. This applies to all sexual partners even those not planning pregnancy.
To check the latest information about risk countries see: www.who.int/emergencies/zika-virus/classification-tables/en/