BEIJING:A coronavirus antibody test that China has made mandatory for arriving travellers has provoked concerns over its effectiveness after one of a team of international health experts was briefly denied entry last week following a positive result.
Although the British expert from the World Health Organization (WHO) subsequently tested negative, it was not immediately clear if the earlier result was a false positive, or the result of previous infection or a COVID-19 vaccination.
Here are details of China's testing rules, potential problems with the policy, its implications for vaccinated individuals and experts' views.
WHAT COVID-19 TESTS ARE REQUIRED?
Travellers from many countries, such as Canada, Germany, Singapore and the United States, must show negative results of nucleic acid and Immunoglobulin M (IgM) antibody tests taken within 48 hours of boarding.
China uses IgM antibodies, normally detected early in infections, as a supplementary tool to filter out those who may have been infected but get a negative result on nucleic acid tests.
However, some cases showed IgM antibodies can persist for a longer time, and even after nearly complete recovery.
WILL VACCINATED PEOPLE GET POSITIVE ANTIBODY RESULTS?
It is possible, but not always, experts say. Most vaccines target the "spike" protein on the virus surface to trigger an immune response that could include IgM antibodies.
"We can assume that any COVID-19 vaccine containing the spike protein will induce IgM and therefore a diagnostic assay designed to detect spike specific IgM will not be able to differentiate vaccination from infection," said Helen Fletcher, a professor of immunology at the London School of Hygiene & Tropical Medicine.
Published data on Oxford University/AstraZeneca Plc's COVID-19 vaccine shows spike protein-triggered IgM is detectable in some people at least 56 days after immunisation, Fletcher said.
IS IT POSSIBLE TO USE DIFFERENT ANTIBODY TESTS?
Tests to detect antibodies triggered by non-spike protein can yield negative results for those who got vaccines targeting spike protein, said Jin Dong-Yan, a professor of virology at the University of Hong Kong.
Vaccines targeting spike protein include those from AstraZeneca, Pfizer Inc and its partner BioNTech, and Moderna.
THERE ARE STILL PROBLEMS
Such tests, however, can be problematic for other types of vaccines, including whole virus-based shots that several Chinese developers use, some experts said.
"Where a person is injected with whole virus-based inactivated COVID-19 vaccine...there's a strong chance that the person may also have positive result from non-spike protein IgM antibody tests," said Ian Jones, a virologist at Britain's University of Reading.
China's health authority does not clarify whether its test is designed to detect antibodies triggered by spike protein or other protein. The National Health Commission did not respond to a request for comment.
CAN VACCINATED PEOPLE ENTER CHINA?
China does not say clearly how it decides to exempt vaccinated people from its requirements for negative antibody tests.
Responding to a query on the topic, one of its Singapore embassy staff said a vaccinated foreigner can submit an immunisation certificate and await a response. China's Foreign Ministry declined to comment.
IS USING A VACCINE PASSPORT AN OPTION?
At November's G20 summit, Chinese President Xi Jinping proposed a global mechanism for mutual recognition of health certificates, including nucleic acid tests.
Experts hope China will consider using a vaccine passport to replace the antibody test.
"A vaccine passport will make travel to China much less of a hassle," said Huang Yanzhong, a health expert at U.S. think tank the Council on Foreign Relations.
"As Western countries achieve herd immunity through mass vaccination, they will start to open their borders... If China continues to have such strict test requirement, its airline, hotel and tourism industries will lose out."
The WHO remains cautious: It refrained last week from advising that global travel be conditional on such proof, citing "critical unknowns" about how effectively the tests limit spread and also their limited availability.
Reuters
Wed Jan 20 2021
People fill forms before receiving a dose of a COVID-19 vaccine at a vaccination site, during a government-organised visit, following the coronavirus disease (COVID-19) outbreak, in Shanghai, China Jan 19, 2021. REUTERSpic
Putin says Russia willing to seek compromises between Iran and Israel
Russia is ready to help seek compromises between arch-foes Israel and Iran, President Vladimir Putin said on Friday, saying these would be difficult but possible.
Indonesia's free meals plan in the spotlight as Prabowo readies for office
Prabowo calls the programme one of the main drivers of economic growth, eventually set to add an estimated 2.5 million jobs.
Astro AWANI's revamped English news website, AWANI International, launches on Oct 21
Astro AWANI's revamped English platform delivers in-depth global news and expert analysis to keep you informed on key developments.
Israeli strikes kill 33 people in Jabalia refugee camp in Gaza, medics say
Residents of Jabalia said Israeli tanks had reached the heart of the camp after pushing through suburbs and residential districts.
Liam Payne's ex-partner calls for media restraint after 'painful' death
Cheryl Tweedy used her statement to urge the media to remember they had a seven-year-old son, Bear, who could read the reports.
Analysts: Indonesia's strong MoF leadership team to boost investor confidence
Sri Mulyani Indrawati as head of Indonesia's Ministry of Finance is expected to instil confidence among investors.
Biden offers both a carrot and a stick to Israel as his term nears an end
Israel has frequently resisted US advice and has caused political difficulties for the Biden administration.
Putin says BRICS will generate most of global economic growth
Russian President Vladimir Putin will host a summit of the group in the city of Kazan on Oct. 22-24.
ISIS Malaysia's perspective of Budget 2025
An excellent rakyat-centric budget under the overarching principle of a caring and humane economy.
Budget 2025: Record increase in STR, SARA aid initiatives
The government will provide a significant boost to the Sumbangan Tunai Rahmah (STR) and Sumbangan Asas Rahmah (SARA) initiatives next year.
Budget 2025: EPF contributions to be made mandatory for foreign workers – PM Anwar
The government plans to make it compulsory for all non-citizen workers to contribute to the Employees Provident Fund (EPF).
What policies to expect from Indonesia's new President Prabowo
Prabowo will be open to foreign investment, his aide has said, such as by offering investors management of airports and sea ports.
Budget 2025: Govt allocates RM470 mil to empower women's participation in PMKS
The Women's Leadership Apprenticeship Program will be intensified as an effort to produce more female corporate personalities.
Israel sends more troops into north Gaza, deepens raid
Residents of Jabalia in northern Gaza said Israeli tanks had reached the heart of the camp, using heavy air and ground fire.
Indonesia ramps up security ahead of Prabowo's inauguration
Prabowo Subianto will be sworn in as Indonesia's president on Sunday with Vice President-elect, Gibran Rakabuming Raka, also taking office.
Immediate allocation of RM150 mil for local authorities, DID to tackle flash floods
Datuk Seri Anwar Ibrahim said this allocation is intended to address the recent flash floods that hit the capital and several major towns.
Budget 2025: Sabah, Sarawak to continue receiving among highest allocations - PM
Sabah and Sarawak continues to be prioritised under Budget 2025, with allocations of RM6.7 billion and RM5.9 billion respectively.
NFOF will be operational in November 2024 with funding of RM1 bil
PM Anwar Ibrahim said NFOF will support venture capital fund managers to invest in startup companies with RM300 million set aside for 2025.
Minimum wage to increase to RM1,700 effective Feb 1, 2025
The Progressive Wage Policy would be fully enforced next year with an allocation of RM200 million, benefiting 50,000 workers.
Bursa Malaysia ends higher on Budget 2025 optimism
The benchmark index, which opened 1.85 points higher at 1,643.29, moved between 1,641.71 and 1,649.31 throughout the trading session.