Analysis: Cambodia’s Vaccination Drive

Phnom Penh is now more vaccinated than most large cities will ever be.

Quick facts

1. Around 95% of Phnom Penh’s (PP) adults have had one dose
2. Around 90% have had two (methodology stated below)
3. Phnom Penh yesterday finished giving first doses as it moves to other provinces
4. Over 2/3 of Kandal adults have had 1 dose, whose 2^nd doses are due in the next two weeks
5. Sihanoukville, Koh Kong Kampong Cham, Kampong Speu, Takeo and Svay Rieng have also started their vaccine rollouts
6. Cambodia is the 11^th most vaccinated non-European large country globally
7. Cambodia’s 9^th most willing to take the vaccine out of 116 countries surveyed
8. Whilst most countries use an age-based vaccine rollout, Cambodia’s is location-based
9. 3.62M first doses have been done in Cambodia, 21.9% of population, 36.2% of adults
10. 2.76M fully vaccinate people are here, 16.7% of population, 28% of adults
11. 6.38M doses have been given, 38.7 per 100 people
12. Over 100k doses have been given over each of the last two days

Country comparison

Local media sources praise Cambodia for being second in ASEAN, but the achievement is far more significant, as Cambodia ranks 11^th globally for non-European countries with a population over 5M according to the Financial Times vaccination tracker. Note that Cambodia is 8^th on this list & chart for fully vaccinated people, but UAE, China and Saudi Arabia are highly vaccinated but data isn’t broken down between 1^st and 2^nd doses.

Cambodia’s rollout pace is also impressive compared to other countries with a 7-day moving average of around 80-100k over the last two weeks (or 0.6 per 100 people). The following visual is a screenshot from the Financial Times vaccine tracker:

Willingness to get vaccinated

According to this poll done in the latter half of 2020, Cambodia ranked 9^th out of the 116 countries surveyed as 84% said they were willing to take the COVID vaccine. Laos & Thailand and Vietnam were also at above 80%. The lowest statistics were mostly around the former USSR (Czech Republic at 38% and Kazakhstan at 25%), but USA, Spain, France, and Italy also scored low. It is worth noting though that almost all countries (including Cambodia) have since seen a higher rollout than these rates predicted.

Targets & supply

When Cambodia first announced that from April, 1M doses would be distributed each month, many were intrigued. Three months these targets have not only been met but more than doubled. Cambodia is aiming to vaccinate 10M people which is around 95% of its adult population and around 60% of its total population (as the median age is as low as 26), however higher targets may be taken if children are also vaccinated.

Cambodia is well underway to procure the 20M doses required for this, with 9M in country currently and a further 5M planned before the end of July.

Of these vaccines, only 3% are western vaccines (AstraZeneca) though, and almost all have been used. Cambodia is due to receive an additional 700k vaccines (likely AstraZeneca) via the COVAX scheme but ever since India stopped exporting vaccines it is unclear when this will come through. In late 2020, Cambodia expressed its preference for Western vaccines, but unfortunately most countries outside of North America or Europe holding out for western vaccines (even those with large pre-orders), has been disappointed time and time again leading several to resort to the Chinese vaccines.

Whilst the effectiveness of Sinopharm and Sinovac is well below the mRNA vaccines Pfizer and Moderna, almost every scientific study concludes that the reduction in severe hospitalisation and death is over 90%. Last week, Reuters, CNN were published that “350 health workers have tested positive and dozens were hospitalised”, but absolute numbers are meaningless, we know that 130k health workers had been vaccinated in Jakarta alone before March, but even using this number, it’s only a 0.3% positivity rate and furthermore, “dozens” out of 350 could be 30 (8%) or 300 (86%).

From my research, no vaccine is underperforming. The first wave of vaccines was aimed at stopping people getting very sick. The mRNA vaccines (Pfizer and Moderna) however have an added unexpected benefit that they are able to reduce asymptomatic spread by as much as 90%, more is explained in this superb article, but Sinovac, Sinopharm, AstraZeneca, Johnson & Johnson, Sputnik are all very successful at reducing serious COVID cases significantly.

Why a location-based approach?

Aside from vaccinating vulnerable professions, almost every country’s vaccine programme is age based starting with the most vulnerable oldest people and working down progressively (with certain exceptions such as health professionals and people with pre-existing health conditions), in contrast, Cambodia’s approach has been largely location based.

Only 8% of Cambodians are over 60 and around 38% are under 18. The vulnerable population seen in other countries is very small, which is echoed in the low death rate of around 1% currently.

Cambodia’s urbanisation rate is as low as 24% and it is widely thought that COVID spreads considerably more in highly urbanised areas. Even Thailand has a 49% urbanisation (more than double) whilst both other bordering countries, Laos & Vietnam are both around 36%.

Since Phnom Penh houses the vast majority of the nation’s 4M urban citizens, the location-based approach seems sensible in Cambodia more so than in other countries.

Vaccine rollout timeline

1. Cambodia’s first batch from Feb to Mar 2021 was 300,000 military (who would assist with vaccinating later batches).
2. Batch 2 was over 60s in Phnom Penh in late March mostly using AstraZeneca (this seems to be around 50k but exact number is unknown)
3. The third batch in late Mar-early Apr was then profession based and more broad as certain sectors/employers were vaccinated such as health professionals, journalists, teachers, diplomats, INGO workers were some included here, up to here. Several ministries were distributing vaccines with the Ministry of Labour doing the most. In mid-April Phnom Penh went into a lockdown for three weeks and 1^st doses were almost completely halted, and by the end of April 1.3M first doses had been issued.

After the lockdown was eased though, Phnom Penh adopted its unique location-based vaccination programme.

• The fourth batch targeted Phnom Penh’s red zones (areas with highest infections) from early May 2021. Around 100% of adults (over 1M) people living across six districts were vaccinated, namely Mean Chey, Dangkao, Kambol, Pou Saenchey, Ruessei Kaev and Tuol Kouk districts. 1.02M in total were vaccinated in a region where 0.98M adults reside (note these are district populations as many outside the red zones but in the districts were vaccinated here). Percentages may be above 100% as people from outside these specific areas may have been vaccinated here plus population counts are not exact (see methodology below).

Later Phnom Penh batches

From late May until late June, Phnom Penh’s remaining 8 districts opened incrementally, each would have a strict 2-week period for first doses and then two weeks for vaccination (with usually a couple of days in between) to honour the 2–4-week interval period recommended for the Sinovac vaccine. Batch five was Sen Sok & BKK, batch six was Chankarmon, Chhbar Ampov and 7 Makara, batch seven was Preaek Phnov, Doun Penh and Chrouy Changvar (note many of these batches overlapped). Although this completes Phnom Penh’s list of 14 districts, Kambol (a district with a red zone) was later added to vaccinate people who were not done during the red zone period. With this, on 23 June Phnom Penh’s vaccination programme completed its first doses (with 2^nd doses expected to end on 8 July).

The next chosen provinces

Kandal Province started with Phnom Penh last four districts around 10 June. Much of Kandal is considered to fall in the greater Phnom Penh metropolitan area so this was logically the second location. The third province was Sihanoukville, a small province with 3-400k residents started around 17 June, Sihanoukville has experienced Cambodia’s largest per capita outbreak fuelled by its casinos.  Fourth was Koh Kong a few days later, an even smaller seaside province with around 150k residents which is experiencing a large outbreak (compared to its population) over the last few weeks.

Four highly populated provinces are next in line starting around 22 June, Kampong Speu, Takeo, Kampong Cham and Svay Rieng with combined population of 3.5M and over 2M adults have started in the last couple of days.

According to this WHO report, the 8 provinces in stage 2 transmission also known as localised community transmission are Phnom Penh, Preah Sihanouk, Kampong Speu, Kandal, Takeo, Kampot, Banteay Meanchey & Svay Rieng. All of the provinces vaccinating at the moment are included on this list except Koh Kong (which is experiencing a newer yet significant outbreak).

In determining the next regions, a few factors will be considered. Kampot and Banteay Meanchey (both with casino related outbreaks) are on the stage 2 transmission list, Cambodia’s plan to welcome tourism back in Q4 will be dependent on Siem Reap’s vaccinations, whilst neighbouring Battambang has almost 1 million residents.

What about herd immunity?

When a virus is unable to find enough hosts to keep spreading, a concept called herd immunity is achieved and the virus will eventually die out, generally achieved through vaccination or through natural infection. Over the years we have seen smallpox completely eradicated and other viruses like measles & polio very well contained. Throughout 2020, herd immunity estimates of 60-80% were often discussed, i.e., when 60-80% of people are vaccinated. Unfortunately, it is not so simple, herd immunity is impacted by a variety of factors such as a country’s age distribution and frequency of other health conditions in the population, the variants present, which vaccines were used etc. Even the UK pushing one of the world’s fastest vaccine rollouts has had new infections rise to the highest level in months due to the emergence of a new variant, to when the vaccine program was in its early stages. The screenshot of the chart below is from Bing’s COVID 19 statistics

Despite Cambodia’s impressive vaccination programme, its unlikely to be a silver bullet, where no new cases are present, but if almost everyone in Cambodia is protected from severe hospitalisation, then Cambodia will have won this battle.

Methodology

1. 16.5M is used as the nationwide population which matches most sources including the FT vaccine tracker
2. 10M adult population matches the targets set by the Cambodian government.
3. Phnom Penh is assumed to have 2.77M people, this is 21.5% higher than the 2019 census shows Phnom Penh to have 2.2M, but the census adds the population side to 15.5M which is 1M below the UN & World bank estimates ranging between 16.5-16.9M. 2.77M in Phnom Penh is 25% higher than the census number, to account for this population difference plus Phnom Penh is assumed to grow the fastest and lastly to account for unregistered foreign nationals.
4. Phnom Penh is assumed to have 78.5% adults over 18, which is far higher than the national average of 68.4% according to the 2019 census, giving an adult population of 1.96M
5. It is impossible to explore whether 196 countries’ vaccine strategy has not been location based, but the multitude of articles researched imply that this approach has not been taken elsewhere.
6. Each of Cambodia’s 25 provinces are subdivided into districts which are in turn subdivided into communes
7. Calculating Phnom Penh’s amounts

If PP’s adult population is just under 2M, 95% of adults is 1.9M, so if 45% of item 2 is assumed to be in Phnom Penh, 100% of 1 and 0% of item 3, then 95% first doses and 90% is achieved.

Submitted by, and copyright of David Benaim