Dr Doug Stephenson, acting chief medical officer, said: "Our junior doctors make up the bulk of our medical workforce and we are highly dependent on them.
"We've invested heavily in our junior doctors over the last few years, dramatically increasing their numbers, so the consequences of many of them striking is that we only have enough senior doctors to provide urgent care.
"We will need to reduce the number of patients in the hospital over the period leading up to and during the proposed industrial action, deferring planned surgery and clinic visits, which creates a lot of angst for our patients."
Stephenson said hospital doctors and managers have spent a lot of time on contingency planning to ensure patient safety over the 73 hours of the strike and said he had personally worked overnight shifts in the Emergency Department during the last strike in October.
"This will be the third time in four months we've had to shift all of our energy and a significant amount of time to cover the roster to assure patient safety. Although the second strike was called off in November, much of the planning had already been done."
Waikato DHB says most of New Zealand's 20 DHBs will be affected by the action, which will involve a complete withdrawal of labour by RDA members.
The Waikato DHB's hospitals in Thames, Te Kuiti, Taumarunui and Tokoroa are mostly unaffected by the strike.
Stephenson said: "We appreciate our senior doctors' assistance and will be doing all we can to provide them with support during the strike."
"We are reminding the public to keep our emergency department for emergencies only. If your illness or injury is not urgent you may face long delays. It's better to go to your family doctor or local private accident and medical clinic when symptoms first appear rather than becoming seriously ill and needing emergency services."
• Waikato Hospital has set up a helpline number for those who are unsure about their appointment: 0800 276 216.
