July 21 (Reuters) - Johnson & Johnson (JNJ.N) on Wednesday forecast $2.5 billion in 2021 sales for its COVID-19 shot and set a lower production target for the vaccine as lengthy manufacturing problems took a toll. The company now expects to produce 500 million to 600 million doses of its one-shot vaccine this year, Chief Financial Officer Joseph Wolk told CNBC on Wednesday, down from its original goal to produce a billion shots this year. J&J offered no timeline on Wednesday for when it would resume production at a problematic Baltimore plant, which had been expected to produce vaccines for Europe and the United States. The company expects to record more than half of the projected $2.5 billion in sales in the fourth quarter, Wolk said on a conference call to discuss financial results. It reported $164 million in COVID-19 vaccine sales for the second quarter, bringing total sales to $264 million so far. J&J estimated its vaccine price at $5 per dose in the first half of the year and said it would likely be as much as $8 by year end. The healthcare conglomerate, which promised it would not make a profit on the vaccine during the pandemic, said the fluctuating price reflected the net costs of the vaccine and production volumes. The $8 price is a bit lower than previous indications. South Africa has said it is paying $10 per dose for both the J&J and the two-shot Pfizer/BioNTech (PFE.N), vaccines. AstraZeneca Plc (AZN.L) is charging $3 per shot for its two-dose vaccine. While the J&J shot was authorized in the United States just a few months after those from Pfizer and Moderna (MRNA.O) were cleared, its vaccine sales outlook pales in comparison and reflects the widening gap in the global vaccine race. Pfizer and Moderna have forecast $26 billion and $19.2 billion in annual sales of their vaccines, respectively. Analysts have said that lower demand for J&J"s vaccine should not affect the enormous company"s overall financial performance. J&J reported second-quarter earnings per share of $2.35 on sales of $23.3 billion. Revenue for all the vaccines could jump if health officials determine a round of booster shots is needed should evidence show COVID-19 immunity is waning. "It is simply too early to provide specific information on a 2022 outlook for our COVID-19 vaccine given the uncertainty on the need for boosters and new variants," Wolk said. J&J had previously said it expected to be able to make as many as 3 billion vaccine doses in 2022. The J&J vaccine appears to be durable for at least eight months and effective against prevalent coronavirus variants, Wolk said, citing recently published data from laboratory studies. Because of its one-dose convenience and less onerous storage and shipping requirements, J&J"s shot was once touted as an important tool for vaccinations in hard-to-reach areas. But after safety concerns and manufacturing stumbles, it has the lowest uptake in Europe among all the vaccines approved for use, and has also struggled to gain traction in United States. read more Its vaccine has been linked to a very rare, potentially life threatening blood clotting condition, similar to AstraZeneca"s. U.S. regulators last week also added a warning related to a rare autoimmune disorder. read more The U.S. Food and Drug Administration in April said its inspection found a long list of sanitary problems and bad manufacturing practices in the Baltimore factory run by J&J"s subcontractor Emergent BioSolutions Inc (EBS.N), shutting down production. read more The FDA has so far approved five batches from the Emergent facility since production there was paused, and J&J is working to clear additional doses for use, Wolk said. J&J did not comment on other issues facing the company, including liability lawsuits related to its talc and pelvic mesh products, or the recall of five of its sunscreen products after it detected a cancer-causing chemical in some samples. read more Reuters reported on Sunday, citing sources, that the company is exploring a plan to offload liabilities from widespread Baby Powder litigation into a newly created business that would then seek bankruptcy protection. read more J&J shares were up 0.2% at $168.80.