The gap is due to a shortage of rapid testing kits used to screen thousands of residents at a time, according to state media.
Hanoi medical institutions and hospitals have been assigned to boost testing capacity.
Rapid tests can diagnose a blood sample in minutes but are prone to inaccuracies.
They are used to identify potentially positive cases that are confirmed using the more accurate, swab-based polymerase chain reaction (PCR) test.
Phan Quoc Viet, chairman of PCR test kit manufacturer Viet A Corp, said he was not concerned about stocks.
"Vietnam is not short of Covid-19 test kits," Viet told Reuters. "We have enough for two million PCR tests and are willing to provide enough kits for the country to conduct a widespread testing program".
(Writer: James Pearson | Editor: Martin Petty)
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