Investigations are being conducted into the source of a Covid-19 outbreak in Tonga, according to the prime minister Hu’akavameiliku Siaosi Sovaleni.

The virus is suspected to have been transmitted from one of a number of merchant ships that had delivered aid to Tonga over the last two weeks.

Tonga went into lockodown at 6pm on Wednesday after two port workers tested postive for Covid-19.

At a media conference Thursday, the government said the total number of positive Covid-19 cases in Tonga now stands at four – down from five originally announced on Wednesday.

Prime Minister Hu’akavameiliku along with Minister of Health Saia Piukala said that one of the first two reported cases has come back negative and are both still in isolation.

The prime minister said that the negative case will undergo three more tests before being released.

The lockdown is strict, requiring everyone to stay at home (exempting frontline workers), to wear masks when entering public, and shutting down non-essential services which includes retail and wholesale businesses.

Just three hours before Wednesday’s lockdown, three new cases were announced, the wife and two children of one of the port workers, who are being confined in isolation at Tonga’s main medical facility, Vaiola Hospital.

The first two Covid-19 cases were both frontline workers who had been loading aid deliveries from foreign vessels. They have since been confined in isolation at a Tongan military base, Taliai Camp.

Prime Minister Hu’akavameiliku told RNZ Pacific that they were investigating the outbreak, and that it was unlikely to have been transmitted from naval boats that had delivered aid to the country.

He said that the two port workers who had contracted Covid-19, had been collecting aid deliveries at Queen Salote Wharf, a separate port of entry from Vuna Wharf, which was used by the HMAS Adelaide, a Royal Australian Navy boat and the only vessel to have reported Covid-19 among its crew.

Before arriving off Nuku’alofa, the boat had isolated 29 of its crew after they tested positive for Covid-19. The ship was required to follow strict protocols, with crew dropping aid on port, spraying it, and immediately retreating to their vessel. Tongan frontline workers would than wait 72 hours before collecting.

“The naval ships use the Vuna Wharf whereas the merchant ships go on to the Queen Salote Wharf. So there’s two key port of entry, depending on the type of ship coming in,” the prime minister said.

“At the same time, some of the naval ships actually went to Queen Salote Wharf, but there were contactless deliveries for the boats in place whereby there was no contact whatsoever between our local workers…so we are confident that it’s unlikely to be one of those naval ships as the source for this particular two cases.”

Limited techonology to identify Covid-19 in Tonga means that the country relies on labatories overseas to confirm test results. Samples have been flown to Fiji and Australia to be confirmed.

“We’re sending a sample of the original two positive cases over to Australia on a third flight today, just to find out what the variant is, and hopefully we get get some ideas on the origin of that particular variant or whether it’s Omicron or Delta. And hopefully that will help to determine where it actually originated from,” Hu’akavameiliku said.

The outbreak is a blow to recovery efforts in Tonga, occurring less than three weeks after the Kingdom suffered a devastating volcanic eruption, that resulted in entire villages being destroyed by tsunamis and the country covered in ash. Many are in urgent need of water and telecommunications remain down in most of the country, with phone calls unable to be made into the Vava’u and Ha’apai group of islands. Hundreds have been left homeless, including residents evacuated from small outer islands.

The disaster along with the Covid-19 outbreak, is a turbulent start for Tonga’s government that was elected to power late last year. Prime Minister Hu’akavameiliku had only formally been sworn into parliament days before the disaster.

“It’s hard. I mean, having to deal with the volcano and tsunami, and now with with the outbreak of Covid-19,” he said.

“It has been very challenging to deal with trying to get relief assistance in a Covid environment, in a very restrictive environment, applying the Covid-19 protocols for the work…even though it’s a challenging time but the satisfying thing is that we are here to actually help,” he said.