Since the Philippines announced that it was finally planning to reopen to foreign tourists, the discussion has shifted to the three lists — Green, Yellow, and Red — that determine how travelers from each country are treated, especially for quarantine. These lists are apparently based on those developed by the US Centers for Disease Control and Prevention (CDC).
But even the US does not use the CDC lists to set its policies. These lists are merely recommendations for its citizens planning to travel overseas.
There are in fact five lists, including an “Unknown,” because data are insufficient to determine health risk levels. Several countries in the green list, including the perplexing case of North Korea, were on this list until the Nov. 22 update. There are inconsistencies in the CDC’s lists, and these are compounded when consolidated into three lists.
These are just two compelling reasons to question the usefulness of the current three lists being used in the Philippines to set entry policies. How then should it go about reopening its borders to foreign tourists safely? It is useful to look closely at the current criteria employed and assess their effectiveness in safeguarding public health.
Infection and vaccination rates in source countries are the main criteria used in setting entry requirements. How useful are these criteria? If there was no testing requirement or the tests were highly unreliable due to lengthy incubation periods, for instance, then the source-country infection rate could materially affect the risk of importing the virus. However, since the incubation period of the Delta variant is only about seven days, the likelihood of a false negative is much lower with this now-dominant variant.
There is evidence that testing is a sufficient safeguard, whatever the infection rate in source countries. Between Sept. 8 and Nov. 1, only 14 imported cases were detected among 13,731 travelers who entered Singapore under its quarantine-free Vaccinated Travel Lane (VTL) scheme. This is about one in every 1,000 travelers. None of the 14 cases led to community outbreaks. The fact that Singapore has VTLs with both low and high infection rate countries, including the two (Netherlands and Faroe Islands) currently on the red list, has not mattered.
In short, the evidence shows that pre-departure and post-arrival testing can reduce the risk of importing the virus, to such a point that the infection rate in source countries becomes almost irrelevant in setting differential entry requirements.
The same principle also applies to the vaccination rate in source countries. If the vaccination status of inbound travelers can be verified, then the overall vaccination rate is also essentially irrelevant.
Vaccination rates are more likely to affect the supply of tourists, which may be the binding constraint for quite some time, together with other push factors such as quarantine on return.
If the levels of infection and vaccination rates in source countries are relatively unimportant, it then follows that differences in them across countries are even less so, especially if they are minor. This calls into question the usefulness of grouping countries into too many categories, and applying different quarantine requirements. The fact that these levels and differences are continuously changing compounds the problems, and adds to the administrative burden without any compensating benefit.
Highly risk-averse countries could choose to isolate outlier countries with persistently high or explosive increases in infection rates. This is a negative list approach, where all other countries are treated equally, irrespective of their infection or vaccination rates. This approach would involve a consolidation of the current green and yellow lists, while retaining the red list.
The best way forward is to focus on the protocols themselves and apply them equally or independently of the source country. In this region, Cambodia has adopted this approach, in common with most of Europe and North America. The Philippines should do the same, or at least employ a negative list approach, based on its own assessment and needs.
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Jayant Menon is Visiting Senior Fellow at the ISEAS-Yusof Ishak Institute in Singapore.