Luohan Academy

Measuring Population Virus-Resistance

On the last day of 2020, the World Health Organization approved the first COVID vaccine for global use. The world entered 2021 in a new phase of the pandemic economy: the vaccination phase. By mid-March, more than 400 million doses of vaccines had been administered in over 100 countries.

As spring arrived in the Northern hemisphere, in a small number of countries with high vaccination rates, people were getting ready to welcome spring for their economies. Israelis were partying like it's 2019. Iceland, Maldives, and Seychelles were accepting fully vaccinated travelers without any testing or quarantine measures. The UK kicked off a four-step roadmap out of lockdown. And in the U.S., many college students swarmed sandy beaches in Florida.

When and how to relax strict social-distancing and lockdown policies remain open questions. Can we reach herd immunity or is this goal still necessary? How far are we from normalcy, and what kind of "new normal" will that be? The Luohan Academy's Pandemic Economy Tracking (PET) project has developed a new indicator system, namely the effective population immunity rates (EIR), to help answer such questions. It aims to inform decision-making by policy makers and the general public in this vaccination phase of the pandemic economy.

The EIR is not another vaccination tracker, of which there are plenty. The indicator is calculated using publicly accessible vaccination information and takes into consideration the time required for human bodies to develop immunity after vaccination. More importantly, it also includes immunity attained through past infection. Therefore, it is a measurement of the overall virus-resistance level of a population and thus directly comparable to herd immunity thresholds, be it 60%, 70%, or higher.

We propose a set of rule-of-thumb thresholds as general principles to help inform adaptive recovery strategies from the pandemic. A country's EIR (from vaccination and past infection) tells us which rung of the ladder to pandemic normalcy it occupies

Schematic depiction of the sub-phases of the vaccination phase of pandemic economy

The rules are as follows. A country enters the "early" vaccination subphase when it starts to gain effective immunity from vaccination (EIRv). This subphase lasts until EIRv reaches 20%, by which point the priority population – essential workers and vulnerable elderlies – are mostly covered. The "middle" vaccination subphase commences at EIRv of 20%, during which lockdowns can be partially relaxed. The "late" vaccination subphase starts with total EIR of 50%, until herd immunity is reached. In this period, tools such as vaccine passports, enabled by digital technology, can help lift an economy to a quasi-normalcy situation – most activities and businesses can go back to normal, with some restrictions.

We tracked changes to the vital signs of the pandemic economy before and during vaccination, such as death rates, positivity rate of tests, mobility, and policy stringency across a number of countries, especially the frontrunners in the vaccination race. By carefully analyzing Israel's successful re-opening, the Seychelles' death surge following pre-mature relaxation, and the UK's carefully designed roadmap out of lockdown, several key learnings emerged.

First, fast vaccination works best when accompanied by strict lockdown, especially during the early vaccination subphase, by establishing a double-shield system for key workers and vulnerable populations. Second, the relaxation of social distancing and lockdowns need to be step-by-step, matching the level of effective population immunity, and rolled out in an adaptive way. Third, digital technology can be an important assurance in implementing both vaccination and lockdown with precision, for example through app-based vaccine registration systems. In short, vaccination alone is no magic bullet, but if carefully coordinated, vaccination and social distancing can and do form a powerful two-pronged strategy for taming the pandemic adaptively and robustly.

While lessons from the frontrunners are encouraging, around the world large disparities still exist and the road out of the pandemic is still long and winding. Due to vaccine hesitancy and the continuing emergence and spread of new virus variants, more and more epidemiologists think that we might never reach herd immunity for COVID-19 in many countries. Or in other words, the virus is here to stay and may come back in waves like the seasonal flu.

World map of countries in various subphases of vaccination. As of March 16th, 2021, Bahrain, Seychelles, UAE, UK and USA are the five countries in the "mid-vac" subphase, while Israel, with the highest TEIR of 51%, has reached the "late-vac" subphase.

The world will experience a couple of waves of recovery. Advanced economies and some emerging economies will lead in the pandemic economy's recovery, starting from summer 2021, while most others will lag behind. While this big trend seems unavoidable, minimizing this gap by getting people in all countries vaccinated as soon and as widely as possible is not only ethically important, but also makes a strong economic case. Similar to the need for a globally concerted effort to contain the virus in the early phases (especially the preparation and response phases, which did not happen) global coordination in the vaccination phase is even more critical. Closely monitoring and analyzing population-level effective immunity rates provide us with a necessary light to navigate the ocean of this phase of the pandemic economy.

For more details on the conceptual framework, methods, and analyses of effective immunity rates of 185 countries and regions worldwide, please refer to our report "Navigating the Vaccination Phase of Pandemic Economy – Implications for Adaptive and Robust Global Recovery." Related data can also be downloaded from there.



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