The withdrawal of Zostavax from the shingles market is complicating the calculation of the National Immunization Program.

In the government's 'National Immunization Program Priorities' study, there had been a large gap between the priorities of live and recombinant shingles vaccines, but with the number of live shingles vaccine options being reduced to one, the need for more options has increased considerations.

In late May, MSD Korea reported to the MFDS the discontinuation of its shingles vaccine, Zostavax. The final stock-out date is difficult to predict, but the discontinuation will bring to an end a nearly 15-year run of the drug since its approval in April 2009.

Upon the withdrawal of Zostavax, the remaining options in Korea will be GSK's Shingrix and SK Bioscience's SKYZoster. The two vaccines have distinct characteristics. SKYZoster is a live attenuated vaccine, which means it is easier to access due to the lower costs required for its vaccination than its competitors.

On the other hand, Shingrix is an inactivated vaccine that can be administered to immunocompromised and immunosuppressed patients who have previously been unable to receive live attenuated shingles vaccines. However, the high price and the two-dose regimen are considered hurdles.

The shingles vaccine is one of the most common non-reimbursed vaccines, and with the withdrawal of Zostavax, its use is usually left to market choice. However, the issue arose with its planned introduction to the NIP. In the government's mid-to-long-term plan for NIP, the shingles vaccine was divided into live vaccines (SKYZoster, Zostavax) and recombinant vaccines (Shingrix).

Live vaccines ranked 5th vs. recombinant vaccines ranked 15th among all vaccine priorities

To summarize, the live vaccine was ranked 5th out of 15 vaccines, while the recombinant vaccine was ranked 15th and last. Although both were for shingles, they were prioritized differently.

In a literature review of the effectiveness of live and recombinant shingles vaccines, live vaccines were found to be effective in 9 studies compared with a control group, but their effect decreased over time.

In the case of recombinant vaccines, a total of 9 studies reported their significant vaccine effect, with 2 studies reporting a significant effect when assessed 7 years after vaccination. Despite the longer duration of effect seen with the recombinant vaccines, live vaccines are higher up on the priority list because of their cost-effectiveness.

A cost-effectiveness study on implementing a live shingles vaccine for adults aged 60 years and older in the NIP found that its implementation was not a cost-effective strategy in the short term, but was cost-effective in the long term.

Compared to the current self-vaccination practice, its introduction to NIP was analyzed as a cost-saving strategy from a societal perspective. Also, the ICER tended to decrease with age, when assessed in 60 to 75-year-old subjects. Another study found that the cost-effectiveness of the vaccine would be maintained at KRW 85,000 and that the cost-effectiveness would decrease if the cost of the vaccination increased above  KRW 95,000.

However, recombinant vaccines are expected to have greater uncertainty in terms of cost-effectiveness compared to introducing a live vaccine, although information on the exact pricing of recombinant vaccines was limited before the launch of Shingrix late last year.

In the actual study, the annual estimated cost of the shingles vaccination support program for people aged 70 and older was about KRW 28.2 billion for a single dose of the live shingles vaccine and KRW 98.3 billion for two doses of the recombinant vaccine, which is a threefold difference.

Fewer options remain for shingles vaccine...attention focused on the expanded influence of Shingrix

Given the effectiveness and cost of the vaccine, the researchers concluded that introducing a live shingles vaccine in the NIP was practical.

The problem is that at the time of the study, there were two live vaccine options, but with the withdrawal of Zostavax, there only remains 1 live vaccine option in the market.

It would be difficult for SKYZoster to enter the NIP alone given the multiple aspects that require consideration, including price competition.

In particular, it is more inefficient to supply both live and recombinant shingles vaccines at the same time than to introduce live and recombinant shingles vaccines separately for people over 70 years of age.

In addition, the growing presence of Shingrix since its launch may rise as an issue for the government in the future.

Last year, Shingrix’s sales reached KRW 38.4 billion (IQVIA) and rose to No.1 in the country. In the same period, rival vaccines SKYZoster sold KRW 26.2 billion and Zostavax sold KRW 22.3 billion.

At the time of its launch, the vaccine was criticized for its high cost, as it costs up to KRW 600,000 for two doses, but it has been gaining share in general hospitals based on its strength as a quadrivalent vaccine that can be administered to immunocompromised individuals and its high prevention rate of over 90%.

As a result, it is hard to ignore Shingrix in the shingles NIP discussion amid the vaccine’s rising market share based on cost-effectiveness alone.

However, it remains to be seen whether the pharmaceutical company will be able to accept the cost of vaccination set by the government. Currently, it is not possible to confirm the cost of Shingrix vaccination from HIRA’s non-reimbursed medical expenses information, but it is observed that its cost per single dose is in the low KRW 200,000 range on site.

An industry official said, "With the withdrawal of Zostavax, there are many considerations that need to be made in the discussion of introducing shingles vaccines in the NIP, including vaccine type and price. As price is important for NIP in addition to effectiveness, how these points are coordinated in the future will be an important factor in the entry of NIP."