By Juliet Samuel 

As Greece goes to the polls Sunday, investors are bracing for a volatile reaction in markets. But some analysts say the wider impact is likely to be contained.

The results of the vote are all-important for the future of Greece, but their broader effects will be cushioned both by Greece's isolation from the euro-zone financial system and by the massive program of bond-buying launched by the European Central Bank on Thursday, said Lucy O'Carroll, an economist at Aberdeen Asset Management.

"The contagion is not completely gone," she said. "But it is reduced."

Analysts at AXA Investment Management said markets could be volatile in the aftermath. "The uncertainty caused by negotiations between Greece and international lenders is likely to take its toll on risk assets, in the euro area at least."

But they added that even if the radical left Syriza party wins on Sunday, Greece's elections are likely to have either a "marginal" effect or "no material impact on the rest of the euro area."

Markets in Europe are still digesting the full impact of the ECB's announcement of quantitative easing which itself came just days after the Swiss National Bank shocked markets by removing the Swiss franc's cap against the euro, sending the single currency plunging in the days since.

In the two and a half years since Greece's government last collapsed, Europe's banks have slashed their exposure to the country's banks and sovereign debt and the region's other struggling economies have made significant steps towards stability.

Greece's borrowing costs have decoupled decisively from those of Portugal, Ireland and Spain, which recently reached record lows even before the ECB announced it would start monthly purchases of EUR50 billion ($56 billion) in sovereign bonds.

By contrast, markets are still demanding a yield of 10% to lend to Greece for two and a half years, whereas its 10-year bonds are paying yields of around 8%. Markets often charge more to lend short-term when investors are worried about the prospect of a default.

Markets shouldn't write off the possibility of some contagion from Greece, said Peter Westaway, chief economist at Vanguard Asset Management in Europe. "Greece is still a little bit ringfenced now [but] there's almost a complacent view that Greece is completely off the radar, " he said.

A spokeswoman for Syriza denied that any victory by the party would be taken badly by markets. "Our victory will mark the beginning of a different era, for the whole of Europe, in which economic growth and development will take the place of austerity measures," she said.

Opinion polls indicate that Syriza is likely to win but without enough votes to form a parliamentary majority. Assuming it can form a coalition with another like-minded party, negotiations over the terms of Greece's bailout with the country's international lenders, the European Commission, the IMF and the ECB, could drag on for weeks. If Syriza can't form a government, new elections will have to be called.

Greek stock markets benefited from the ECB's decision to start quantitative easing last week, despite a warning from ECB president Mario Draghi that Greek government bonds wouldn't be eligible to be bought by the ECB until negotiations between Athens and its international creditors reach a satisfactory conclusion. Shares in Greece's biggest banks rose by between 6% and 14% on Friday.

Write to Juliet Samuel at juliet.samuel@wsj.com